I DEFINITELY don't buy that they're Morbius, that's for sure. A guy who takes himself that seriously would never wear a top hat.
As far as the Doctor's concerned, I like not knowing- it's a mystery better left unsolved. Going by other things Neil Gaiman's written about the Corsair, it's probably not him/her. Chronotis is a fun idea though. But the idea that it was a lie definitely fits, and I wonder why more fans haven't gone with that, since the general proposal that it's Morbius is preposterous when you watch how the actual scene plays out. But I like the idea of pre-Hartnell incarnations maybe or maybe not existing. There's plenty of hints for it in the series- pretty much all of Season 25 and 26, plus the Third Doctor's slip about being thousands (plural!) of years old. Like "the Caretaker", I think the less we know about where the Doctor really came from (and where he's ultimately going) the better. It'd be awesome and hilarious if they did some tiny callback to the Morbius Doctors at some point, just to help stir up confusion. Moff loves to troll the fans so much I could see him going there.