The power with MARVEL is that they are separate films. You have people who have never seen any of the MARVEL films going to see AVENGERS. You have people who have only seen IRON MAN going to see AVENGERS. You have people who have only seen THOR going to see AVENGERS. And sometimes you have people who go see them all, but this has yet to be seen in action among the masses. And did not seeing these tags negatively effect how they viewed AVENGERS in any form, sort, or way? Absolutely not and if so - I've never heard any complaints about not being able to follow it due to films and tags that came before. MARVEL knows that not everyone will see every tag, this is why they are making them solo yet together units rather than just "to understand you must see them all." I'm way more familiar with people who have seen IRON MAN and just AVENGERS than all of them.
I also know many that didn't watch all the Fast and Furious films, most i know sometimes don't even watch their movies in order. That's besides the point, what i mean is, imagine for exemple an Iron Man 8 or whatever that is supposed to tie into a Secret Wars kind of film along with all the other MCU films, However they all fail one way or the other, then Marvel has to change their strategy and they have to drop the foreshadowed stoyline due to budget. There are a lot of different ways a planed story arc can be dropped, or fail, that's the problem, if that happens then they need to give an half-****d explanation.
From the development of Batman and Alien movies you can see many ideas have to be dropped, film is a business, and business can sometimes be unexpected.
ALSO they already hit their first big bump in the road with IRON MAN 2. Did Iron Man 2 really hurt Avengers? Nope. Did Iron Man 2 really hurt Iron Man 3? Nope. So, your hypothetical scenario has already happened. Plus, I really can't see another MARVEL film being as poor as IRON MAN 2. It will happen, but IM2 did absolutely nothing to hurt the forward momentum.
A lot of people can disagree with that statement of Iron Man 2, it even received relativelly positive reviews, and the audience liked it, it also did very well in the box-office.
Obviously you wouldn't do it if you didn't know for 100% sure what the next film is going to be, that's plain and common sense.
Unless the plan fails, studios normally like to change things in production to suit their idea of what makes a film more successful.
You weren't talking about 2020 or the future - you were quite clearly for everyone to see talking about present day...
Then to back it up listed ****** movies no one had any interest in seeing a sequel to regardless of a tag or not. Films perceived by the masses to be terrible do terribly.
Because it happens in the present day, and yes my intention was allways that it would happen in the future, not the present. Why did i list thos movies? Because if you can't learn from the past you're going to commit the same mistakes.