I will keep my keepers regardless the market. I actually already now do not care how much they are worthed. I just care owning them, forever.
But of course the argument makes sense for non-keepers. Although there are diffeent segments (new nib, new huo, b/w, ss, etc), I think at the market as a whole: the more machine in decent to good conditions available, the more new blood is needed to sustain the prices. I think Stern is the biggest offender. And actually the only one making money at the moment. But if they keep flooding the market with many machines, prices will overall drop. Not so much on the most popular titles, -most people will keep them - but much more on weaker titles.
Probably Stern plans to grab as much as they can now with nib machines. And after the market for nib will significantly drop, they will focus on selling parts for older machines.
I guess BM66 stupid price is only a classic one-off marketing trick on a bad game for later decreasing the perception of increased prices on future machines. They anchor 15k in your head (as being silly, of course), so that later on you think 6.3k is not that bad after all.