First step:

Increase community, make MK1 "free" game, you can play it for free but only 5 champions which rotate evry week, you can preview skins not wear it until you buy the game, which also need to be -50% cheaper.

Description: Without big community game is doomed from start, right now MK1 is game for hardcore fans and rich kids, (prove: In PvP even on low ratting you meet guys who play godlike)

BIG community is pillar of gaming society

Second step:

Drive carrot on stick, once you build up community offer people reason to keep playing, tower ladderboards etc, not only PvP be creative

Third step:

Ensure people that you care for game, instead making mortal kombat 500, evolve your current game, so people know if they earn skin, buy skin, grind skin that it gonna matter forever.

Fourth step

Do smart microtransaction politics, people buy skins and stuff ONLY if they like the game, and when they know skins they buy today will be viable in decade.

-There must be cosmetics which are easy to get

-There must be cosmetics which are grindy to get

-There must be cosmetics which are prestigeous

-There must be cosmetic which people can buy because your company must earn to keep game up.

-Increase cosmetic slots as well, dont limit youself only on armor and jacket

Intresting fact:

In World of warcraft hourse mount in microtransaction store earned more money than entire Starcaft 2, people buyed it because they want to invest in good product.