After the 'epic' double download of 'Sniper and Spy', all that is left is Demo, Engi and Soldier.
Having no clue what to expect, apart form beta tests and sketches being a possibly or guideline. New weapons, new levels and possibly new hats are all to be assured or at least considered. Maybe the Engineer will get a new building(s) (or upgrade) that detects spies; The Soldier obtains a new rocket launcher which burns; Demoman gains access to trip-bombs blowing up the careless.
The team of Team Fortress 2, have clearly out done themselves not just with the gameplay quality but also 'Meet the' videos. They have been improving slowly, yet to be released are the Medic and Pyro. We can expect much entertainment from both of them.
We'll have to wait and see...