Quickplay killed a lot of community servers because the main method of finding a game was now limited to servers running under a set of rules that most community servers did not run under. Non-regulars stopped going to "non-standardized" community servers, and the regulars weren't enough to keep them alive, so they ended up petering out. The only community servers around today tend to fit into one of three groups:
1) being really weird and/or non-standard (rtd, orange, mariokart, saxton hale, deathrun, etc.)
2) "training" maps that might as well be category 1 but i felt they needed a distinction (skill surf, jump, mge)
3) servers that still fit quickplay criteria like map rotation and sv_pure settings (i may be wrong about the specifics of quickplay restrictions so feel free to correct me)
(Note: None of these categories run the maps that this community produces. That'd be a fourth category of server that used to exist.)
I think the major problem with this update so far is that it needs community servers that don't yet exist. From what I understand, community server owners are very excited by this update for the exact opposite reasons they hated Quickplay.
I'd like to see Valve bring back Quickplay only if it's less restrictive on what servers it can dump you into. Effectively, a "random" button on the server browser already in the game (maybe excluding the "weird" and "training" categories I already listed). Sure, you can already do this yourself with the server browser, but that's just not good design.
As for the casual matchmaking system, I think it just needs to be faster and smarter. I'm not sure if I mind the abandonment penalties as a concept, but it's leading to shitty situations like 9v12 matches you can't leave unless you want to get punished. The matchmaking system should be able to fill those slots quickly, and there needs to be an outlet for people who want to join/leave matches as they please. Without either of these things, the "new pub" that system is supposed to create just isn't getting a fair shake.
tl;dr: things are a mess but this update is laying ground for things that I really hope are yet to come.