I thought that split A3 rumor was debunked. And no reason to spoiler wild fan theories. Honestly, no reason to split it, not like it's based on a book or something and they're cutting an established story.
I dunno, reading now the one debunking sound like equally wild speculations.
"Marvel isn't splitting Avengers 3 into two movies, but they are planning Avengers 3 as the springboard to... something else. And they're going to use their biggest characters in that something else, keeping them out of Avengers 3."
That makes no fucking sense.
As for why you wouldn't want it, because those movies are shitflecks compared to what Marvel has built. And there's not much way to reconcile the movies happening in the Avengers U without any kind of acknowledgement prior.
Now, if they made their OWN Spider-Man he could fit in awesomely. But the Sony one? Fuck no.
I dunno, I'll wait for part 2 and the other 5 or whatever movies in between before I worry too much about part 3.