Since there have been other mergers & different forum cultures (United/Continental, Northwest/Delta, American/USAir), my guess is it will be similar w/ Marriott/SPG. The 2 programs aren't formally merging until sometime in 2018, so I'm assuming the mods & the CD will/are working behind the scenes on it/some of the issues & have time to sort out some things/integrate before the two programs formally merge. But I know the CD looks for input from members as well.
Cheers.