Considering how much "Oldhammer" miniatures go for (or how much Ebay sellers dream that they go for at least), I hardly think any old Specialist Games miniatures are in for a price drop. Especially not with a potentially expanded fan base.
I think the idea of one-off box sets is likely given that it has been rumoured for years (i.e. planting the concept) *and* is in line with the recent collectible, limited miniatures strategy of GW. If for no other reason, it let's them test the waters at low risk. How that approach would measure up against fully supported games from competitors would be interesting to see.