Ironically enough if there are changes or dropping of the travel packages before the final merger, it might be due to the stampede of SPG elites transferring points to Marriott to redeem them
Right now no one knows. The 2 programs won't be totally implemented until late '18/early '19, but doesn't mean there might not be some changes on either program before then. My guess is (and it's only that) is that since the programs won't merge for a year, the travel packages will still be Marriott only & not SPG properties. If the OP is saving & thinks he'll have points by end of year for '18, he'll probably be ok.
Cheers.