Sorry to bring gloom and doom, but fighting games almost always use servers exclusively for matchmaking (finding an opponent).
Netcode is still one of the things that many developers seem to get wrong for fighting games (at least we're to the point where everyone expects online play, but unfortunately there are still plenty of examples of great implementations (Street Fighter 4) and bad implementations (Tekken 6, at least when it first came out (and for quite some time after)). I think in a lot of cases they consider it lower priority/something to worry about later/something that won't affect sales so much (as long as the box says it's present).
It's been shown many times that it's possible to have great netcode in the most intense of fighting games these days, as long as both players have a sound connection.
My biggest hope in case the developers didn't have time to really make online as good as it can be is that they at least are able to find the time/have the tech. to truly improve the netcode after release vs. do nothing or making tweaks that don't really address the core technical problems.
I will def. be a little let down if MK's online isn't ideal within a few weeks of release -- my friends who will play this with me are not around for local play (and I think this is prob. the case for many of us older MK fans). I would be content with this MK as a single-player package, but still...
My other hope is that NRS isn't just following the SF4 formula with this -- get this one out the door and add more content/improve features later via double or triple-dip re-releases (which can be highly profitable for companies but not so great for consumers (if we start having to buy three versions of our favorite games)). I don't think this is likely as they seem to have really crammed this one with great characters/content.
Praying for great netcode/online at release or soon after!