When asked just that, Minear stated, “Yeah, I mean, he’s going to be moving to what’s in his future. And look, Tommy is in Buck’s romantic past for sure. But that doesn’t mean that Tommy is necessarily not ever going to intersect with Buck in this universe again. “Tommy is always going to be somebody who kind of opened a door for Buck, and that’s an important thing to be in somebody’s life.” - Tim Minear, TVFanatic
In other words Buck and Tommy won't ever be in a romantic relationship again but Tim left open the possibility they might still run into one another or talk again. Although in my personal opinion I don't think it will be where they'd actually bring Lou back to the show, not after all the drama they've had to put up with from the actor himself and his fanbase. I can see them doing something in the future though, after Buck and Eddie get together were maybe Buck mentions Tommy or where there's a some kind of scene like in s2 where Tommy does something to help out the 118 but we don't actually have to see the character.
I'm honestly just hoping that 806 was the last we've seen of Tommy altogether. I'm sure Bummy fans will try to twist what Tim said somehow but having the show runner explicitly state that Tommy is in Buck's romantic past for sure is a really specific way to phrase that when he could have left it much more open ended. It just feels like he's trying to say that chapter of Buck's story is closed now.
