Personally, my pet theory about Savitar’s identity was that he was Barry from the future.
Now, it sounds like I may have been wrong on both counts.
My backup theory was that Wally is actually Savitar, although that was mostly based on my belief that wearing a mask with the top cut off and going by “Kid Flash” would be enough to turn any adult a little bit evil.
Savitar has said “future Flash” more than once in Season 3, and given that The Flash tends to go more for spectacle over subtlety with its supervillains, my money was on a plot twist that would turn our mostly lovable Scarlet Speedster into the grim Future Flash of DC comic canon.