Mad that the game had potential and also we could've had Poison playable earlier, but the loyalists panned the game to death to have it cancelled because of "OH NOES!!! SIDESTEPPING!" Also we had finishing moves, though they were in the Super Dragon Ball Z territory inputs (Piccolo's star input, i.e.)
I feel that TxSF won't be a thing ever, if they'll make it then the Tekken players are going to be pissed about the SF ("2D") characters and they'll forget about the game very quickly and go back to the x numbered Tekken game they were playing before that, leading to the death of TxSF in like a year, max two.
Tekken players can't be mad about 2D characters in a crossover title, that's ridiculous! if it was a mainline title i would understand but the whole point of a crossover title is to try new and whacky things. well if they're that mad they can always go back and play Tekken 7, oh wait they hate Tekken 7, well then they can go back and play Tekken 6, oh wait they hate that game as well