I didn't mean literally be a pain in his ass. But I would love for this question to be answered sometime in the very near future. I actually have a feeling since this fighting engine is an improved version of the Injustice one(which didn't have a tag mode) I don't see MKX getting a tag team mode either.
For balancing sake it may be tricky to set up double teams and such due to the 3 variants we get for each Kombatant. If they can't figure out a way to balance this. My suggestion is to do the UMK3 tag system where you fight until you die and then your next character comes in. Meaning no tagging in and out like MK9. It's not ideal but atleast it's some kind of tag mode right??