Why did a singluarity not form when Thawne killed Barry's mom? He changed the past. Why did one not form when he killed Wells and his wife? When he killed others, like Iris's boss? Why did he not fear such an event would happen if he killed Barry as a child?
As we see in the Dr Who series, the basic problem is that alternate time lines will be created/erased. so would there really be a new future reset, or just a new timeline from that time forward, and there would still be history as they know it, so RF still lives then?