They updated the overall timeline with this info:
http://comicsalliance.com/your-supermovie-timeline-updated-with-marvel-studios-phase-three-releases-infographic/The problem I see, from my layman's perspective, is that they're going to have to introduce unfamiliar superheros. For me, I am totally in the dark about Ant-Man, Black Panther, Suicide Squad, Dr. Strange, Sinister Six, Cyborg, and Gambit. Stuff like Aqua Man I only know from the Superfriends cartoon.
So whereas some things unfamiliar to the lay perspective -- such as Guardians of the Galaxy -- have another hook (sci-fi actioneer), the more solipsistic personal journey superhero story (like Ant-Man) is going to fall flat outside of the target audience, yes? And how big can that target audience be?
But no matter what, we round back to my rebuttal of your presumed piece: We've never not had a superhero movie in cinemas or on TV for four decades now. This current glut may blow up in their face on one level... But the gamble now is the same gamble it's always been -- it only takes one hit to make the return investment. Guardians of the Galaxy, and anticipation of the sequel regardless of the fate of the genre, will keep them afloat well into the 2020s. It's the same gamble the publishing industry relies on -- Harry Potter's success makes it possible to publish 100 other books that either flop or run the middle ground.
Coupled with income from TV -- a far more reliable and far greater return on investment than movies -- and you're home free. Even at the "cult favorite" level, a TV show will rake in the cash. Season one box set sales of Agents of SHIELD alone will pay for any potential losses in, say, Ant Man.
When you study the timeline, you see the tent poles strategically placed. 2016 will be supported by the X-Men/Captain America summer blockbuster double-shot. The others can flop and die all they want. 2017 will be supported by GotG/Thor doubleshot. The season opens with a little cash bump from the Hugh Jackman Fan Club to make up for losses at the end of 2016, 2017's bets have been hedged by the always reliable Lego family income. 2018 -- summer doubleshot again with Avengers/X-Men. Inhumans (Groot) at the end of the year again cashes in on the kiddie cash.
The pattern each year is the same -- sacrificial lambs that may or may not become hugely popular are supported by the movies that are and always will be popular.
And will the audience burn out? No. Because it was known in the 1970s that the audience craves superheroes. Feast or famine, the craving is always there (which rounds back to the other thing I talked about a few posts back -- the genre has spread into all the genres. You could call Unforgiven a superhero movie).