Dark Matter is one of three things:
a) A flaw in our understanding of gravity at extremely large scales. This has, and is, being tested extensively as does NOT appear to be the case, based on multiple lines of evidence. This would be revolutionary.
b) A new massive (as in: having mass) electromagetically neutral particle or particles. This seems most likely. Some particle models account for these and the LHC may be capable of generating some such particles. They may or may not interact with the strong and weak nuclear forces as well and many neutrino detectors are being upgraded to attempt direct detection. This would be evolutionary.
c) A gravitational interaction between massive objects in different universes on nearby branes, as gravity can move between branes in these models. This would be M-theory model universes, not MWI universes. This would be revolutionary.