I bet it's Arno Stark.
See that would make sense but so far the changes to the Big Three haven't made sense. Remender had been building up Ian Zola to be the new Cap and now suddenly it's Falcon and by all accounts it looked like it was going to be Angela that would replace Thor but now it's some random new character.
I want it to be Otto after leaving Spidey, like, OK PETER YOU ARE A HERO AND YOU'RE THE TRUE SPIDER-MAN.... BUT STARK'S AN ASSHOLE AND I CAN DO BETTER THAN HIM
SUPERIOR IRON MAN