Thanks for supporting the idea even if you might not ultimately support rift watchers as the vehicle. RiftWatchers as the vehicle is tricky. It's been out a while and people have different connections to it. For me I don't care about the set and would just assume watch it burn if I didn't think it would be better used to burn far more cards.
What I want more than anything is for players to want to buy Rebellion packs. I want the team to stay afloat. I think the biggest deterrent to buying packs is the idea that cards are infinitely inflationary.
So I'm going to push back on your logic here. While I think cards holding their value or increasing in value is important for pack demand, I'd say that's negated when everyone just watches the packs burn to no fanfare. Did it really hold value if no one is buying it?
I think they will take that same lack of enthusiasm with them to the next set if anything short of skyrocketing prices happens to RiftWatchers. And I think what's actually going to happen to riftwatchers is that many people who bought those will start selling them to get funds for rebellion so their prices will fall to their lowest levels as rebellion gets closer instead of popping because the set is sold out.
There is no catalyst on the horizon for a spike in Rift Watcher prices between now and Rebellion and its doubtful we get one before the following set because that's when they'll cycle out of modern.
Ultimately, I think RiftWatchers has already seen its peak and its not going to inspire anyone to buy more packs (its not even inspiring people now to buy riftwatchers packs now). But setting a precedent that shows cards aren't infinitely inflationary, burning a tons of them, and watching riftwatchers go out with some demand? That might inspire some buying.
Anyway, that's my thoughts. I can see it both ways but I think watching RW burn to no fanfare could be a disaster coming into rebellion.
RE: Burn cards for Rift Watchers packs (EDITED TO MATT'S PROPOSAL for a burn event)