If...*IF,* god help me, the Avengers (and the MCU phases in general) are set up on an overarching three-act structure of some sort, and Thanos is "the fireworks finale" for TA3 as some of you believe, then he will, of necessity, be the driving force behind *TA2* as well as TA3. Just as he was for TA1 (yes: unnamed and unseen until after the credits, Thanos is actually the villain who drives the action in TA1, *not* Loki....Loki is merely doing Thanos' bidding, whether "Reindeer Games" is aware of that fact or not). TA1: Thanos maneuvers from the shadows; TA2: Thanos takes a more hands-on onscreen role, even though he doesn't directly confront the Avengers; TA3: Thanos vs. Avengers in The Big Showdown.
Absolutely. There's even more Hi-Ev ties to MCU characters than that, but I won't laundry-list them; and he could also plant the seeds for other heroes/villains who haven't even been discussed (much) yet --- Spider-Woman, for instance.
I'm starting to think that rumormill murmurings of "The Controller" and "The Collector" evolve (pun intended) from confusion (or even outright disinformation) about the High Evolutionary, and that Wyndham is really the guy they've been talking about all along: i.e., Wyndham is a genetics genius on Earth who's starting to "evolve" humanity with superpowers (The Twins being examples) in his isolated stronghold on Mt. Wundagore, and Thanos (and/or even The Other, who some of us liken to Marvel Comics' Chthon, which would create a *direct* canonical connection to Hi-Ev) starts using him as his go-to guy to create an army of supervillains (MoE, in some form or other) to take out --- or at least distract and occupy --- the Avengers so he can go on with his dastardly dirty work.