Ahhh, TF2. I had either forgotten, given up hope, or just pushed it to the back of my mind.
It will NOT be on the .5 life engine, and that notion was scrapped long ago.
They will be using a new engine, and its development alone is supposed to take gaming netcode to a whole new level.
The game should be great, and it will be released.. its just too big a project. Although.. the engine doesn't even have true curves, and since it will be based on massive environments that is kind of a requirement in most games today.. Oh well, lets see what they do.