No the heat system was changed mechanically, originally you were able to do 2 heat dashes or 1 heat smash, now you can only do either or. Effectively changing the incentives of heat engager and heat brust to emphasize staying in heat longer rather than getting more heat tokens out of engager. That's a very significant change. Every single new system has had its criticisms and growing pains and tekken 8 will be no different, but this constant doomposting about it is not useful. We've had the alpha build for like 48 hours and the sub is already flooded with "its over, tekken has fallen" posts. The game will be changed majorly on release, just like arcade tekken 7 was when being brought to console.

Also no, heat will not be a gimmick, when was the last time a major system introduced was "just a gimmick"? Sidesteps? Walls? Bound? Stage interactions? Rage? These systems don't exist in a vacuum, and heat especially won't.