I doubt Marvel really cares about fighting over who has the better king of the sea character right now. Marvel already has most of the plan written out and is currently wearing the crown proudly and comfortable right now. They have the start and end in mind and have left a lot of room in between to include changes like the deal to have Spidey appear now.
So any thoughts what's going to occur Post Infinity War? With so many characters and such brought in think they will either reboot or continue the universe after Thanos is taken care of?
My Phase 4/whatever they're doing post-Phase 3 idea is, Thanos is going to cause so much damage that a time-reversal will be necessary to repair everything. This would cause tiny changes and justify re-casting roles for the same characters, open up the doors for new ones and basically make the sky the limit. One things that bothers me is that Inhumans was supposed to take place before the conclusion of Infinity War and thanks to Spidey entering the scene, the Inhumans is now supposedly going to premiere after the Infinity War is over with. I don't know how that's supposed to work logistically if their main introduction was supposed to be in time for them to join the fight against Thanos but we'll just have to wait and see.
It does seem like them bringing in Spider-Man this late in the game is just going to create more problems than solutions with how it's throwing off the timing and what they're actually doing with the character. How are they going to make his voice sound like an adult's, I wonder? Anyone he interacts with is going to know he's just a kid, plus his size would also be a dead giveaway too. If they want to just change it to Spider-Boy, fine, but pretending he's Spider-Man isn't cool. I mean, there's Young Indiana Jones, and Superboy, and Kid Flash, Aqualad, etc., so it's not like no hero has ever had a 'junior' version of themselves at some point. The least Marvel could do is acknowledge that this character is a mere shell of what he's supposed to become, and that he doesn't deserve anywhere near the amount of cred his future self has earned. But enough beating this dead horse. Trying to make sense of studio execs' decisions is a waste of time.