Will this unite some theories, or cause some other change in physics, and perhaps our undertanding of the universe?
Physicists have expected the Higgs boson to be discovered for a long time, and in fact a lot of theoretical work has been done under the assumption that the Higgs boson exists. So honestly, the mere fact that the Higgs has been discovered doesn't cause any drastic changes in physics. There are no theories that are suddenly far more or less viable today than they were yesterday, for example.
The real question is what kind of Higgs boson has been discovered. There are a few options here: it could be the standard model Higgs boson, which is the simplest kind. If that turns out to be the case, then we've found exactly the particle that was predicted to exist by electroweak symmetry breaking (the Higgs mechanism). That's the most boring possibility because it doesn't suggest the existence of any sort of new or unknown physical phenomenon - particle physics would kind of hit a dead end in that case. (I'm exaggerating somewhat, it wouldn't really be a dead end.)
Alternatively, the particle that has been discovered could be some different kind of Higgs boson, which doesn't behave in quite the way we'd expect the standard model Higgs to behave. That would be far more interesting, because it would strongly suggest that there is something new out there, beyond the standard model, and it would give theorists their first clue as to what it might be. That's the case in which you could get a bunch of new theories that might start to gain validity.
The way we're going to be able to tell the difference between the various options is by collecting more data at the LHC and analyzing it closely to figure out the behavior of the new particle. This process is going to take several years, so we're not likely to find out definite results on this any time soon.
Since Higgs Boson has been theoretically predicted 50 years ago, confirmation of its existence would not change our understanding, it would only confirm existing models. New physics would emerge if it is confirmed not to exist.