What I would have done in marvel's position is start with that pleasent hill storyline with Kobik, than after, overtime, have cap get aged, Thor become unworthy, banner get killed, and iron man go in a coma as it was before, but...
all of these things are connected. A sinister Machiavellian force is minipulating things from the shadows. This force causes Civil War 2, the inhuman/ mutant war, Spiderman gets rich, powerful, and starts a family. He thinks he might retire soon. Spiders life is going great, but heroes are being taken off the board. Some are even disapearing. The remaining heroes begin to realize someone on the inside is responsible. Their's a double agent. Number one suspect is Spiderman, but then TWIST, that was a red herring, his life is just going great, it's really:
Hydra Cap!
He was responsible for everything. He didn't really age, that was faked, with Kobik's help! Remaining heroes are taken down. Then we get the backstory, red skull used a cosmic cube(Kobik) to make cap evil, but now that heroes are gone and everything is all set, cap has turned against him, FOR THE DREAM. His plan comes to a head, hydra begins to take over the world, shield is destroyed...
BUT THEN,
New heroes come forward. Sidekicks and wannabes step up as true heroes.
MILES MORALES
KAMELA KHAN
RIRI WILLIAMS
SAM WILSON CAPTAIN AMERICA
X-23 WOLVERINE
AMADEUS CHO HULK
JANE FOSTER THOR
THE NEW NOVA
They unite together, fight back against hydra, save their idols, old and new unite against evil, hydra cap is defeated, and the truth about the cosmic cube being the cause of his change to a villain is revealed.
A new status quo, new heroes, and set up for the next event:
the search for Kobik.
Marvel's heroes must now find a way to cure hydra cap, and return him to his former heroism.
In the end, they are able to change him back, but evil cap remains as a split personality, that cap must eventually battle to the death for control of his body.