I was thinking that the plot from MK9 should be continued. So after Shao Kahn and Raiden face off in the final showdown, Raiden could maybe intially halt the tournament.

Maybe after a few years pass, Raiden can reign over the tournament to enstill stablity with a tournament with new fighters and new abilities.

Shinnok could flood the tournament with an invasion from the NetherRealms and resurrect the souls of the original cast of fighters that died off while introducing newer fighters from the NetherRealms.

Or Shao Kahn can be defeated and mount a recharge in an advancement in retaking the tournament from Raiden's authority. This can create a heated rivalry between Raiden and Shao Kahn.

Shao Kahn and Shinnok can join forces to overtake Raiden in the next tournament with alliances between good and evil foraging against each other.

Those are just some general ideas maybe with time we can come up with some better ideas.