I myself am very content to have each franchise/character/mythos wait it's turn. Sure, you can have 2 or 3 simultaneously going but between revamps of casting or even outright reboots there's plenty of cooling off time to allow others their shot. Iron Man is my 2nd favorite character of all time(after Hulk) and I've loved how it's gone with RDJ and company but I gotta say after IM3 I'd be totally fine waiting 10 years till they revisited the character and his mythos. I already know they'll never stop making Iron Man movies since the property has proven itself as profitable. So I have no problem if they take a break from time to time. That goes for every other character as well.