Board Thread:The Flash discussions/@comment-11526603-20160517053424/@comment-3423279-20160517091120

Yeah... the series pretty much has to end on Barry and Eobard running back in time to save his younger self (Barry's goal) or kill him (Eobard's goal).

Granted this might not be a neccesary thing; it could continue after that point but your point and the end fight does need to happen while the show is ongoing.