Originally posted by Classic NES
Honestly, the biggest threat might be his "continuous improvement" ability rather than his time-skip. He might get some ideas from thawne and improve as they fight. The problem is DB doesn't have the same concepts of a time stream and whatnot like DC. It's more like a series of streams that cannot change. So, Thawne wouldn't be able to for example kill Goku in the past because it would have no affect on the current timeline as per DB rules.Edit: Also, aging has no effect on Saiyains powers. They naturally age slowly and if you de-age them or turn them into kids their power level would remain unchanged.
Hit is no where near Thawne's level when it comes to Time Manipulation.