3) H.R. Wells
H.R. has been a fun addition to The Flash‘s third season, but it’s hard to imagine how much longevity the character has here. The fact that he isn’t a genius makes him pretty much useless and his unique way of chiming in feels like something which has a limited lifespan. Savitar recently revealed that H.R. survives his attack and seemed genuinely disgusted by him; could it be because he hates seeing his old self?
It’s also worth noting that H.R. and Savitar are the only ones to refer to Kid-Flash as Wallace, a minor detail, but one which might just play a big role in the eventual reveal of the Speed God’s secret identity. If the villain isn’t H.R., then I could imagine him being the Harrison Wells from Earth-2 (mainly due to Savitar’s disdain for H.R.), but that could be hard to explain unless Barry’s actions somehow result in something awful happening to Jesse Quick in the near future.