I have to agree that Turf Takeover is about as good as it's going to get as a mode.
Battle Area works as a competitive/Ranked mode because the entire focus is to vanquish the opposite team and the "no-respawn" premise suits it perfectly as sort of a "Hardcore" difficulty adjustment. With BA it's all about the vanquish count, your skill level with your chosen characters and nothing else matters.
Turf Takeover, however, is objective based so, in my opinion, for any competitive or ranked mode to be successful there would require every player on every team to be dedicated to assaulting or defending the objective. That level of dedication is easy to come by when you put together a specific team of players, the way a lot of us GW2 veterans used to do for the objective based Boss Hunts, but it's almost impossible to guarantee when the teams are decided by drop-in/drop-out play and an often-wonky team balancing system.
To carry the parallel further; for a GW2 Boss Hunt there were a small group of 5 or 6 of us who would automatically try to coordinate our play time so that we could complete the current Hunt on the hardest difficulty as many times as possible for the reward. If we had a newbie or two who we wanted to help get a completion we'd call in whichever teammates might've been online and we'd get it done even if it meant having three of us carry the new person who wasn't quite up to it yet.
Anybody who was into GW2 and tried a Boss Hunt with a random group can attest to the frustration of having one or more people on the team who wasn't playing the objective. For that matter I think we'll be seeing a similar level of frustration in Battle Arena now that it's Ranked since your ranking seems directly tied to your team winning or losing so your Rank could essentially be at the mercy of a randomly assembled team if you aren't grouped up at the time you enter.
Knowing the way the typical Turf Takeover match plays out now I don't think that there's any way to construct a competitive mode around it which doesn't involve predetermined teams, which raises it's own difficulties of eight or twelve people trying to coordinate play times.
