i've already kinda told my side of the story here, but since i came in when this post kinda begun, i'll give more info about it:
to the folks who have mentioned an option in player 1/2 controls, or an option in general to toggle the thok and the new ability... it's very likely there will NOT be it, the main devs have basically already said (in the discord) that an option to toggle sonic's ability will never happen, whether it be an option in the menu, or it be a command, it's either thok stays, or thok will be removed (i find that kinda sad, but the devs have spoken)
obviously, the main reason for the thok being replaced is momentum and it being more accurate to the classics... srb2 has never really been accurate to classic sonic games (besides being a 3d game, of course), stuff like the springs functioning differently or the level design being very different from how sonic 2 or sonic 3 would've done it, srb2 does NOT need to be sonic mania 2, or whatever, it's a fangame for a reason, originality is key
now, i get why the thok would be removed from a conceptual standpoint, i've heard that the thok was only made as a substitute for the fast-paced gameplay of sonic when momentum and slopes were basically a pipe-dream (back in xmas), thus ssn & sonikku implemented the thok, a basic instant speed move, and people grew attached to it
we've kinda made the thok a "staple part of srb2", if the thok was removed in say, final demo or something, people probably wouldn't mind the new ability (as much as we do now)
i'm in support of the thok staying, but i do want to project another side of the story here: the thok was made as a substitute to momentum back in 1998-1999, and srb2 is planning on having it's own momentum. i've made suggestions on thok replacements or thok modifications, most already implemented in other mods (FSonic's thok improved, rebound dash, xmomentum's momentum thok (rebalanced)), but we've only seen a bite-sized portion of what the new ability is, it's been months since we've even SEEN the new ability, letalone actually played it, chances are it's been modified a heavy amount from now, but we will never know for sure
i hope everyone can take this into account when talking about the thok: the thok is (technically) an overpraised ability that was only made as a psuedo-momentum in xmas
hopefully, though, the thok CAN stay as an ability in the game's files, and sonic's ability will either be hardcoded to only function with sonic or be another character ability like the thok (i'm sure the power spin could be useful in some spots before the level design would switch to be more momentum-focused)
basically my stance on it is: i'm definitely still in support of the thok staying, but if the new sonic ability will be as good as the thok, i won't mind too much about it being replaced... i don't even really play match that much, anyway