Both pieces of their business model, advertising and users, strongly benefit or hurt because of network effects. As the network shrinks, the value does not drop linearly. This is an assault from both sides. Because Twitter's growth is now definitely flat and likely is shrinking this is pretty bad.

While you can't do X or Y on Instagram or Snapchat now doesn't mean you won't in the future. Clearly both took a big chunk of Twitter's users. Tweeting pictures was previously a large use case. So was tweeting and sharing things with friends. That you can create a video of what happened rather than typing it out isn't necessarily a different product or use case.

In terms of news - FB, Google, Apple are all going after that market hard right now. The mass use case for Twitter probably made this sub use case look bigger than it was - news and instant events. Things could still change, but it is hard to see Twitter out-innovating their problems when they no longer have the social tail winds pushing them forward. And at some point the cash is going to matter a lot too.

Does it make a lot of sense for someone with a lot of users to buy Twitter and try to revamp it? Plausibly, but the brand damage definitely has been done with the growth demographics. That is kind of the mistake Myspace's acquirers have made. At some point a brand goes from valuable to doing just the opposite.

I bought Twitter shares and ended up selling them all once this settled in. There still probably is a threshold where an executive that is looking for value vs growth tries to acquire and you can arbitrage the difference.

Unfortunately the bulk of Twitter's remaining value is probably going to be realized by there competitors as a case study for the survivors - FB/IG, Snapchat, and future players.

Not to current and past Twitter investors. They expected a lot more.

Some Epictetus or Boethius salve on their wounds, and they'll be alright.

But if users lose enough interest, there won't be anyone to do free reporting for the news media.