I owned Tekken 6 and TTT2. I didn't have to pay additional money for unlocked costumes. We don't know exactly how long we will have to grind for the game money yet, but people already say it will be loooong. A costume costs 4$/€. They for sure won't let you earn that easily/quickly. You basically have to pay money or you turn 100 years old before unlocking all costumes.
By the way, it wasn't mentioned in the trailer but will there even be a simple VS mode? Where I can play single matches against the computer or against another local player?
This game will get shit reviews for all the stuff that is missing at release and all the stuff they want you to pay for.