My armchair guess as to what's going to happen when they merge the two programs is this.

- Today, there are 12 Marriott categories and 8 Starwood categories. (Two of the Ritz categories are dupes and the 8th Starwood category is kind of a loose range.)
- If you merged them together right now and tried to keep all hotel redemption rates flat, you'd need 14 categories, with the 14th being the loose Starwood range.
- Since 14 is a bit daunting for guests - sort of a hard thing to market - my guess is that we'll get 10-ish categories. It won't matter whether the hotel was a heritage Marriott, Ritz, or Starwood brand. Maybe those ultra-pricey Starwoods will get to keep their loose range...or maybe Cat 10 will be so damn high that it won't matter.
- They'll hollow out levels at the bottom: every hotel will "creep" upward.

So yeah, Category 9 *could* devalue. But you probably have all of 2018 to book at current levels (meaning all of 2019 to complete your stay).

Most rooms in the system will cost more to book in 2020 than they do now. My hunch is that the Marriott "currency" will be the one that survives, but the categories will all creep on us a bit.