Marriott has already stated that SPG will remain a stand alone program until at least the end of 2017 so you are fine with 25 stays. SPG may continue for longer than that, could be an extension of MR similar to the Ritz Carlton program, or could be folded into a completely new program. The easiest is to keep things as they are and Marriottt did the deal to retain and expand their customer base. I highly doubt they will do anything at this point to push elite members away.