I feel like the Google Drive/Docs/Hangouts combo pack provides all the things that Wave was supposed to be, no?

All the ground-breaking features, such as live interactive multi-user caret presence are part of Docs. Did Wave promise more than that?

What are the missing pieces that got lost along the way, and never made the jump?

An Open client server protocol.

I think Google Wave debacle is a great example of how the advice/vision dished out on HN is disconnected from the reality of consumer experience/expectations.

With Wave Google saw writing on the wall and discontinued Reader and GChat XMPP integration.

So you're saying Google Wave was an undertaking born directly out of events that happened here on HN?

That's not what I remember about Google Wave. Where are the moments of these facts recorded?

And because that protocol didn't work, they killed off and/or radically altered unrelated chat and RSS products?

I don't feel that's true. Google has implemented other new consumer facing protocols and products since then.

What are the pieces that tie together Wave, Reader and XMPP integration, other than timing and the fact that RSS and XMPP are open standards?

Google Wave was an undertaking born directly out of advice-given/beliefs-held by people similar to those on HN. The advice being all you need is a decentralized protocol like Email/XMPP and its possible to succeed in Social. Google tried that with Wave and failed spectacularly. As a result it stopped listening-to/caring about what tech-savvy users say and started dismantling other open standards social tools such as Reader (RSS), XMPP etc.

Could you clarify what the writing on the wall is ?

That walled garden with better user experience are more successful than open standards where user experience might be difficult to due to issues in changing protocol specifications.

In the short term. It seems to me that long-term the opposite is true. Have there been any studies to show either way?

from what I remember on their demo at some point was they had some cool instant-translation and other stuff built in... forgive the comparison: but much like bots that would do work as you typed. I haven't seen (or noticed) this kind of functionality in docs.