Fire God Liu Kang and Great Kung Lao are given. And if there’s a tournament then Shao Kahn and Goro are too. Kitana and Jade are in their 10000s in the current timeline so they could also show up. And the last one I can guess is Kotal because the MKX comics showed that he was with the mayans when the conquistadors came which was exactly at the time of the Great Kung Lao’s tournament, 500 hundred years before the first game’s tournament in 1492. And there would probably be lots of newcomers.
Who else could you see?
Edit: Raiden, Fujin, Taven, Daegon and Bo Rai Cho could also work. Maybe Geras, working for Liu Kang now instead of Kronika.