Retcon? Time machine? Variants? Nah. Tekken literally just brought Heihachi Mishima back from the dead, and with a new move set. All of Heihachi's hits look like they are powerful, and they hurt. I'm sure Heihachi's resurrection will be explained in the story, but I haven't got there yet.
With Heihachi, comes the Nike cross promotion, and everyone gets the "Nike Air Foamposite One Jin Kazama" for their in game customizable outfits. I literally played a couple of matches online, and they're the first to unlock in the free tier of the fighter's pass, and, they unlock for everyone. Speaking of customization, you can now change the character in the background as you flip through menus, which is one of the coolest visuals in the game.
The new stage is $4.99, and the "internet" is mad. So mad, that Harada-San caught wind and says he will fix that, maybe? A lot of the confusion comes from the fact that you had to pay for Lidia, but the stage was free. This time you have to pay for Heihachi and the stage, which I guess is fine. Street Fighter just gave us Terry Bogard, and I believe you can get his stage with Fight Tickets. I don't know whose side I'm on. I did not get the stage. So there's that.
Here's some non pro completely blind gameplay of Heihachi Mishima. Enjoy!