No Pope could legitimately claim the authority to do the kinds of things the ECUSA has already done. That's simply a fact. No Pope could authorize the ordination of women, for example. No Pope could authorize homosexual "marriage". An attempt to do those things, "infalibly" or not, would simply mean that he wasn't the Pope anymore.
The Pope is a good deal less powerful over matters of doctrine than you think, particularly when it comes to contradicting doctrine that has already been taught at a solemn level.
Ironically, Anglicanism has exchanged the alleged "tyranny" of the Pope for the very real tyranny of apostate bishops who see themselves bound by no tradition except the tradition they themselves invent.