Screenwriters had ideas on how to continue the story, but never had the chances to apply them. It was good that at the start of season 4 they actually dropped the whole temporal cold war arc. IMO that was the weakest feature of Ent. That and maybe the lack of character development when it comes to certain characters, like Mayweather, Reed and maybe Hoshi.
I found it weird that Archer was supposed to care about alliances and ideals that had no reality in his world during seasons 1-3. Whenever Future Guy showed up, I felt that Archer largely won the argument: why should he care about someone else's future? With all the concentration on the Temporal Cold War and the Xindi conflict, the show made little progress toward making interplanetary cooperation part of the Enterprise's universe (save some fealty from Shran). That work didn't begin until season 4.
ETA: for the sake of transparency, I should admit that I was tired of time travel stories by the time Enterprise began. And I started to roll my eyes at things like the ransacked library of the Federation.