5. It May Not Last
Going back to what I said about Sony still holding the rights to Spider-Man and the potential conflicts which could arise between the two studios, bear in mind that Spider-Man's role in the Marvel Cinematic Universe isn't necessarily going to be a long running thing. Based on various reports and comments from Kevin Feige, it sounds like the deal currently only stretches as far as Avengers: Infinity War, so what happens if Sony - now in control of a Spider-Man they're sure can make them money - decides they no longer want to share the wall-crawler with Marvel? That means Spider-Man mysteriously vanishes from this world in Phase 4, something which is sure to feel both very jarring and a major disappointment after we've all just started getting used to his presence there. Sure, it may sound like I'm being pessimistic, and there's no doubt a chance that this deal could last for a very long time if both parties feel it's beneficial to them. However, Sony were developing a lot of spinoffs which Marvel has for now managed to get them to hold off on. Eventually they're going to want to forge ahead with those, and should they fail (and let's face it, a Venom movie with a hack like Alex Kurtzman at the helm is never going to be a hit), then there's no way Marvel are going to want this tainted brand associated with them in any way. The point is, a lot could go wrong, so it's worth bracing yourself for Spider-Man not being a permanent fixture in the MCU, making his upcoming Phase 3 appearances feel anticlimactic to say the least.