It is possible... Warner Brothers owns the Mortal Kombat license, and they have been licensing DC figures for years now. I almost hope we dont see a MK set though... The Street Fighter set was kinda meh. Now if they started making Final Fantasy Clix, I could jump on board with that.
If there is a Street Fighter set, there needs to be a Mortal Kombat set. People have been wanting to compete with the two for years! I honestly think a MK set would sell better BECAUSE there's already a Street Fighter set.
I loved the SF set and hope for another. MK should definitely follow!
I love Mortal Kombat (as many of you may know). I have been working on a custom MK Heroclix set for the past year or so. The set is complete with custom character cards to accompany the custom dials. The set is based off of the newest MK9 video game (and it's characters). I have received dozens of extremely positive comments from realmsers and Facebook users regarding the set. You can check it out on the realms HERE or search "Mortal Kombat Heroclix Need To Be Made" on Facebook.
As for MK clix ACTUALLY being made... sadly I would say don't count on it. While attempting to pitch my set to Justin Ziran (president of Wizkids), he told me that they weren't interested in acquiring the Mortal Kombat license (at least as of a few months ago when I chatted with him about it). Don't ask me why, as I think it would sell even better than the Street Fighter set.