Have to agree with pretty much all of this and have been thinking since endgame about loki disappearing with the space stone that it would have consequences and open up to possible disastrous ones and it does look like its heading that way.
Definitely think Wanda has done some kind of deal with Mephisto to bring Vision back but not realised what Mephisto is gaining from it, as we know in the past Avengers tend to have a habit of intending to do good with very bad consequences (Ultron for example).
One thing that massively pisses me off though is that they haven't re cast the X-Men, I can't stand most the X-Men cast/films apart from Patrick Stewart, James McAvoy and obviously Hugh Jackman but the rest are atrocious, X-Men needs rebooting without a doubt as it was my favourite as a kid then the films ruined it for me (apart from Logan π)
However..... Going back to your point of the multiverse is that it obviously confirms 100% what direction MCU are going with bringing past characters in with the likes of other Maguire, Garfield, Dafoe etc however...... If the Quicksilver of this Universe is dead, where are the X-Men of this Universe also and will they be a completly new cast (fingers crossed) as you would think they have to be as it would and the old cast are included in the multiverse with the other Quicksilver.
Raises alot of questions however exciting ones..... Also now this multiverse is confirmed I'd love to see Hugh return as Old Logan one last time in a timeline before Logan.
Would be awesome especially alongside deadpool.