The Rezound won't be getting the official Sense 4 or Sense 5 updates. However, if you have a good developing community, you can root your phone and then install a ROM that has Sense 4 or Sense 5 inside.
However, to my knowledge, a lot of developers for the Rezound decided to move on because they hated the way people complained a lot about certain function not working (according to some people I know who developed ROMs for the Rezound).