For me personally I'd love to see what Marvel will do with Blade, think they'd make an amazing version while it would still be different enough from Snipes version.

Still am surprised that a universe that Started with Iron Man, has become so far reaching and phenomenal.

Shame we’ll never see Chris Evans’ Cap team up with Wolverine in WWII

What sucks is the Marvel universe is expanding faster than ever, even without the Fox merger, which will likely happen, so I can only imagine they can start consistently expanding with 4 films a year as opposed to 3, because there's just entirely too much to do. I think 3 is their sweet spot, so I'm hesitant despite 4 films a year bringing the perfect amount of waiting time between each new MCU film, but I just think it would be too much on their plate, and maybe there needs to be some sort of prolonged waiting period to build up enough anticipation.

I mean, here's some of the new properties they're likely to touch in Phase 4:
(Pretty much confirmed)
Eternals
Black Widow
(heavily rumored)
Kate Bishop Hawkeye movie
(possible entries)
Nova
Thunderbolts
Fantastic Four
X-Men
(Possible and very likely sequels)
Captain Marvel 2
Captain Marvel 3
Ant-Man and Wasp 3
Doctor Strange 2
Doctor Strange 3
Black Panther 2
Black Panther 3
Spider-Man 2 is the first of the Phase 4
Spider-Man 3(VERY LIKELY due to Sony cranking these out fast)
Guardians of The Galaxy vol.3
Possible Guardians of the Galaxy spinoff(if not multiple spinoffs)
(sequels to possible new franchises)
A sequel to Black Widow
A sequel to The Eternals
(sequels to franchises that may pass a trilogy)
Thor 4
Cap 4
(Team-up films)
Avengers sequels
Sure, some of these may not happen(very few), and some will likely debut in Phase 4, but I just listed 20 and up films just there--Phase 3 only had 10. And I'm sure Marvel has more ideas than simply just the same stuff over and over, we're going to get more projects like Eternals, for sure. So, maybe, 4 films a year is the way to go. But.........Feige knows best, it's just, we're getting spoiled, and the wait for all these new films or new franchises can be excruciating at times.