Sadly I think if the film suffers the same flaws as AOU(as far as pacing and bloatedness) then the 'critics' will be out for blood. If it wants good scores it can't expect any sort of free pass.
Depends on the rewatchability, look at all those films with high OW's, these films have huge rewatch appeal, no matter how good this film is, if it's a bit too "heavy" or "dense" I think the OW will suffer, at this point I'm not too invested in folowing BO numbers, as long as this film makes good bank enough to justify cranking out sequels with higher budgets then I'm happy.
It's clear at this point, the DCCU will be the alternative, the pepsi, the sega to marvel's coke and nintendo. There will be things that the DCCU does that will rub the GA the wrong way but it will endear itself further to those already on board so yeah...I'm not entirely sure WB/DC will ever get Avengers numbers unless they give us a Batman solo film with Joker again.
I personally think one of the big tickets to marvels success is the implementation of novelty. You look at their top three money making movies(two avengers and ironman3) and there is a clear through line of leaning on novelty event status(or directly following it up). If dc wants this kinda money they simply need to lean on it as well as it seems they are gearing up to do so. That they could achieve what they did with TDKT without such efforts speaks volumes as to their actual starting point brand wise.
That being said, after F7, I'm starting to think the death of a key actor played a larger role in some of that success than some would admit. Both in that scenario and in this new one.
I think WB going full in with this cross over approach and cameos and selling momentum and forced relevance is going to have them swimming in money. These past few weeks alone have shown how much more relevance they can lend to their projects by playing the shared universe game marvel has always been playing, it's not just dead show, it's batflecks dead show which means it's mos' dead shot... Alot more relevant than if they had simply made a MOS stand alone sequel(no shared universe announcement) and a SS movie that was also simply stand alone. To rebut your point, I think if they want avengers money they simply need to keep tapping into this novelty approach.
As for your other point about overseas money. I think it's complicated but also very simple. Audiences over there just need to be sold on something that speaks to their what's relevant over there. You'll noticed outside of James Cameron and Inception, few non sequels are actually doing gang busters over seas, it's almost always big sequels. If you aren't a part of something or have giant robots then you kinda have to start from scratch but once you get going then it's on, they will carry you even past your domestic relevance. As seen with Pirates.
I do think certain types of movies do play better in certain regions though, especially if you can speak to their culture and cinematic history. Gentleman Spy and Wizards have big audiences in the UK. Robots, Cars, choreo and a few other things in Asia.
Whatever it was Disney put into frozen cracked South Korea, big time.
BvS and Will Smith and a few other things now that the ball is rolling is probably going to yield some big intl returns imo.
I also think mad max is going to make a killing in China.