The thing is, is that Tekken is first and foremost an Arcade game designed specifically to cater to the Arcade goers. (
Just looking at console Tekken's graphics it's obvious they are afterthoughts) And hence, it's main market and cash cow is Korea, Japan, Phillipines, Indonesia, Australia, etc. where Arcades flourish. That hardcore community is willing to put in thousands of hours and nearly thousands of dollars in tokens over the course of it's lifecycle to play at that level of depth and competition. I doubt Namco would change the system so much at risk of losing that community.
However for TxSF.... that game being a console first game catered to the Western audience, the changes are going to be crazy drastic for that game I'm sure.