No, there's multiple ways to deal with a speedster that don't require other speedsters. People who can manipulate time, create illusions, freeze things (and not lamely like Cold), control minds, control friction, and drain others are all examples of effective superpowers against one, and all off the top of my head.So yeah, creating a "big bad" for Flash each season is pretty much always going to have to deal with the speed force in some way as in the absence of a Lex Luthor type (i.e. someone he can't come at directly) the small time metas and thugs with advanced toys are only ever going to be a temporary nuance.