Overall: nothing.
If all of Facebooks gaffs have failed to bring it down, this surely won't bring down Reddit.
The gaffe here is I can't access Reddit anymore on my phone because the app is gone. It's a little different.
Will those Apollo users go install the worse app, with the worse user experience to continue to use Reddit? Maybe? Maybe not. I won't be. I didn't come back to Twitter when they disabled Tweetbot either.
But FWIW, I exclusively use Reddit through the Apollo app on my phone and have no intention of installing the Reddit app. I may still end up on reddit occasionally with my desktop browser, but I expect usage to drop by 99%.
The only bit I don't agree with is viable competitors, the problem is a little deeper, in that even if there was a viable competitor people still won't move because it's not an exact clone and continuation of their profile (follower numbers, interaction expectations, etc). The rest of your assumptions remain, but I think this is a bit important to talk about so we don't mislead people into creating clones that never take off when they could be creating something new that will take off.
I suspect the users that leave may not contribute much to Reddit's bottom line but their contribution to the community is critical for Reddit to succeed.
A consumer looking at memes is probably okay with the official app but moderators and power users (who tend to post most of the popular content) skew towards third-party apps and tools.
Without those mods and power users, you no longer have anything resembling quality content so even the meme consumers leave.
It doesn't feel vibrant to me at all. If anything, it began as an echo chamber on day one and doesn't seem to want to be anything else. As someone who has been on Twitter since early 2008, it certainly doesn't remind me of an early Twitter.
People tend to talk about things that are salient to them, and disruption of large media institutions hits that button squarely.
I think we like to talk about Digg because it is unique in this regard: the change was rapid and noticeable, due to an intersection of factors (including the existence of Reddit and the ongoing feud-in-jest between them that made many Digg users aware of Reddit).
But most often, I think what happens is that a company enters a long period of irreversible decline: they screw up, forget their purpose or core mission or whatever, but they don't immediately collapse. What happens instead is they become a revolving door for vulture capitalism, and it becomes utterly impossible for anyone to turn the company around. Depending on circumstances, they can coast along for many years, frustrating doomsayers and boosters alike. We could call this, perhaps, the Radioshack Inertial Effect.
So, sure, it's not like Reddit's entire userbase is going to evaporate in the next 12 months. But, Reddit's already been declining for a while, and this isn't making it better. The people at the top probably see the writing on the wall and are looking for their exit. It'll still be a brand in 5 years, 10 years, maybe even 15, but it's never again going to be better than it was yesterday.
This is good or bad depending on who you are. If you're a user who went to reddit to have conversations with people online, it's bad. If you're that user, this API change and loss of 3rd party apps is yet another nail in the coffin.
If you're a newer user (~5 years) who came to reddit for its social media experience and just want a feed to scroll with memes and pictures of cats, this is API/3rd party app drama is entirely irrelevant to you. This is now the majority of reddit by far, which means reddit the company is just fine.
There's nowhere to go for us classic forum people. There is no equivalent to 2013 reddit. I'm would love for this to be a kick in the ass and to be enough to jump start alternatives, but right now I'm not optimistic. Too much focus on decentralization etc. which I think introduces too much friction for not enough gain.
As you say, Reddit has slowly been transforming into yet another social media site. Maybe federated protocols (ActivityPub like Lemmy/Mastodon, ATProto, etc) can win out. More and more of my topically focused conversations these days happen on Matrix and Discord. It's much more like IRC than forums, but it's generally much easier to stay on topic and the smaller crowd sizes make moderation a much simpler process. I'm also just fine with folks like us scattering into niche spaces. Our interests are niche, our habits are niche, a niche space suits us more than the "social media mall." (I also do use social media for more social media like experiences, but I consider that to be separate from chatting topically about my interests.)
I'm goin' back to /. where CowboyNeil at least warned us when he was going to do something stupid.
I use maybe 2-5 subreddits at this point because Reddit has rotted out so much. At least half of those are shutting down permanently as a result of the API changes, and the other half are participating in the blackout. I don't need a shared account across all of those services. In fact, I tend to visit subreddits individually anyway so I don't have to guess about the context of every post.
None of my favorite subreddits rely heavily on photo posts, which keeps hosting costs low. In fact, I notice a strong association between quality and text-only subs, likely because it keeps the lowest quality memes away.
It might not work for every subreddit -- I don't anticipate the denizens of /r/funny would embrace a web forum -- but for hobby, book, and series-related communities, web forums have been around a whole lot longer than Reddit. Reddit only took over because it was marginally cheaper and easier to host; if mods lose their useful mod tools and power users lose bearable and efficient methods of browsing, forums start to look mighty attractive again.
You are already here
It would take less than 1% of Redditors moving to HN to upend the entire culture here and make this place look like Reddit 2.0.
"Please don't post comments saying that HN is turning into Reddit. It's a semi-noob illusion, as old as the hills."
Those complaining are vocal minority that will mostly continue to use Reddit through official app/website.
They're mostly Reddit addicts and they're probably not going anywhere.
It's the power users that's a different matter. The people most engaged with Reddit are likely to be among those who actually participate and make posts. If you see a drop in creators and commenters then we've got a degradation of the entire system.
I see myself as a commenter, a mid range user. I comment often but have posted only three times in 10 years. Without those posters then I'm gone by default even though I don't use third party apps. We'll have to wait and see which segment decides to leave.
"Providing an API costs money", but so does providing chairs for your employees to sit on, yet that doesn't seem like such a crazy thing to be doing "for free".
These are the people powering Reddit, without them it is nothing.
I will say, I think Discord could benefit from this. They have a forum like product and any subreddit trying to migrate has already been having this discussion. The overlap of users is insane.
I do use Reddit on my laptop quite a lot - but only with the Reddit Enhancement Suite. Take that away and I am gone, the plain website is pretty bad. But then again I am probably not the target user.
Most subreddits already have a Discord server anyways, and most active Reddit users have Discord accounts. Every other alternative is or would be an upstart.
The technical issues you have could be addressed by pivoting the software.
>I also find that most of the messages tend to be pretty mundane chatter; people are just filling space.
This is similar to my experience, but I think it's because the only Discord servers I am on are similar to Freenode IRC channels, they're programming related or related to a specific technology and the primary reason I'm on there (and most) is to get help when stuck (and I try to reciprocate by answering some questions when I can too.) The primary purpose isn't social.
But from what I have heard, it's used very differently by younger people. There's communities around shared interests or just for specific friend groups etc...
[0]: https://m.fark.com/
For comparison, when Digg 2.0 came out, people just moved to Reddit immediately, they didn't complain about it on Digg, and vow to leave eventually. They just left and never looked back. I'm generalizing; of course there are counterexamples.
I think we've made an internet where there aren't a ton of viable competitors, so there is no easy path out. The choice is to either get the dopamine hit from the same place as before, or forego the dopamine hit altogether, and for a lot of people the answer is clear.
I'd love to be wrong about this though.