Given that it has platform versatility, that is a huge plus and it's convenient to play with friends.
I know it won't be like D2 or D3 with numbers, but I think from the active communities of MK I've seen out there, we could have decent numbers here.
Keep in mind, there are few other MK (online) series games that have smaller numbers than MK X, which could add further volume when considering the whole series.