If bucket pricing goes away let it. We will just refuse to pay high bucket fares, so let Amtrak discover for themselves that higher buckets mean less revenue, If higher bucket prices only is really the new rule, then Amtrak just won't have many customers left. It will be a cold day in hell before we pay $400-$600 for a bedroom on an overnight trip.
I hate to break it to you, but while Amtrak Unlimited folk may be Amtrak's most knowledgeable and enthusiastic patrons, we're a very small fraction of their total ridership. Whether you're personally willing to pay that much or not doesn't matter a whit. Whether everyone on this entire message board is willing or not doesn't matter. Lots of people are probably willing, and it only takes several dozen per train to fill the sleepers. Amtrak has doubtless done the calculations (assuming they actually have changed their pricing policy -- all we have to go on is scattered anecdotal evidence so far).
Who knows, it may hugely alter the demographics of Amtrak sleeper ridership. It may kill off the use of Amtrak sleeper accommodations by Americans using Amtrak as a mode of transportation, in favor of foreigners using it as a "rail cruise" almost exclusively. But I doubt it will reduce revenue. And (though it's unfortunate for many of us) Amtrak is actually a business, with very limited resources and a mandate to do the best they can revenue-wise. If this move increases revenue, it is the correct thing for Amtrak to do.
In an ideal world, they would be able operate like a revenue-maximizing business
and have the freedom to acquire enough sleeper cars to fill all demand at a variety of pricing levels. We know that with a bucket system making low fares available, Amtrak's sleeper cars still break even above the rails.
But we don't live in that world. We live in a world where Amtrak has only two or three sleepers per train, ever. And we live in a world where luxury vacations have become much more the thing to do than they were in, say, the 1940s. Perhaps Amtrak has realized there's a better way to run their business to maximize their revenue given their resources, by taking advantage of the potential for larger sleeper profits to offset other losses.
If their plan works (if in fact this is their plan at all -- we have no idea), perhaps they will gain some leverage to ask for more sleeper cars per train. Who knows. Of course, that would take a decade. That doesn't work well for you. But it may work very well for Amtrak.