Devaluation definitely coming around the corner. I've been at this game too long to think otherwise. ADRs are climbing, occupancy rates are climbing. Hotels aren't needing to entice travelers to stay with them.
They've essentially already done this with peak / off-peak awards on this chart. One of the main benefits of using Marriott points was during higher-price times. The new chart shows that they're going to be narrowing down that loophole.
The only positive I see in this is that we're getting enough notice to cash out points at the current rates. I don't think it's going to be a huge devaluation, but it definitely will be a positive step for hoteliers and a negative one for customers.