https://www.youtube.com/watch?v=hiY1AQjIaP0
^^ God damn this dude fucking nailed Barry = Savitar. Props. I know a lot of people, even myself, felt like it was going to be Barry, but those were mostly shots in the dark -- this guy just lays it all and catches every little hint beyond the "I'm the future Flash" line that started most of the Barry=Savitar theories.
I was constantly thinking it still just doesn't make sense (post-reveal); how does past Barry see Future Barry (Savitar), and still become Savitar? How does emo long hair Barry not know who Savitar is or why does he lie to Past Barry when he says he doesn't know (when he knows it's himself)? Well it makes sense if Past Barry does everything in his power to prevent turning into Savitar after Iris dies -- which leads to him ridding himself of his inner darkness because he knows somehow somewhere some future part of him becomes Savitar, but he doesn't know how -- which in turn actually creates Savitar (inner darkness Barry who is now trapped in the Speed Force, beyond time), and that newly created Savitar knows the only way it (Future Barry) exists is if Iris dies (so that Barry rids himself of his inner darkness) and so it has to go kill Iris, creating the loop.
It also explains why when Barry talked to his future depressed self, his future self didn't say much and that he didn't know Savitar. This is because he (Emo Barry) knows that he finds out who Savitar is before Savitar actually kills Iris (when he is Past Barry), and yet it changes nothing. So it doesn't matter if past Barry knows or not; Iris is still going to die even when he (past Barry) tries to change up the timeline, and eventually learns of Savitar's identity before Iris actually dies (because emo Barry also found out who Savitar was before Iris died and she still died).
Still a bit messy as all things time travel, but makes the most sense to me. The question with time travel though is always what created the first loop though, this makes sense from the perspective of how does past Barry know he becomes Savitar yet still becomes Savitar, but not how the very first Barry (that created the loop) actually becomes Savitar? That might go unexplained or originate in a Future Flash (like the comics) explanation or something to do with Reverse Flash (back when he said he's going to change one thing).
Alternatively they just retcon/trample over everything they've told us and Savitar is just a time remnant left to die or just Flashpoint Barry and wouldn't know all of these Barry quotes or events.