Another possibility would be for Steinberg/Yamaha to sell the original Motif sound set (maybe even including the Motif ES/S90 ES sounds) as a Halion expansion, including full editability. The vast majority of these sounds aren’t included with the modern Motifs or the Yamaha Montage, and those that are are very useful for layering.
I know a lot of people would buy it for a more accurate recreation of the Power Grand alone. That piano is immensely popular.