I think there will continue to be a lively resale market in Weaver for a long time to come. Most of the product is scale size, rugged, and nicely decorated. Also, Weaver produced by far the widest variety of railroads and other brands on their rolling stock. If you want, say, a wood-sheathed boxcar lettered for the Green Bay & Western, Weaver is your go-to brand.
A couple of responses to comments posted above:
Locomotives: Weaver diesels don't sell well on the secondary market. I think this has a lot to do with the obsolete electronics - there's an awful lot out there with QSI-OEM, Proto-1, or plain QSI reverse boards with no sound. Supply exceeds demand for this level of technology. Even their TMCC offerings are mostly either first generation or TAS, which is an orphan product. Most of their molds were sold to MTH, which is selling the same engines with upgraded detail and modern electronics. Nonetheless, the remaining Weaver engines will be around for a long time. Electronics can be replaced, and at the prices they are bringing these days, Weaver diesels are a bargain.
On the steam side, Weaver made a lot of unique, high-end brass steamers. Many of these had mechanical problems, but there are still quite a few of us out there who are willing to put the work into maintaining them, simply because if you want, say, a Milwaukee Road F6a Baltic or a Lehigh Valley streamliner, it's worth it.
Jonnyspeed mentions the two-bay covered hoppers. This is a very early mold, and IMHO the worst thing Weaver ever built. I have half a dozen of them for the unique graphics, but I agree they are a lousy design. The good news is that everything else is better. The older boxcar and reefer designs are OK, if a bit short on detail. The flatcars are fine. I could use a few more if I could find some lettered for Milwaukee Road. The last of their freight car designs, the B&O wagontops, the Milwaukee ribsides, and the TOFC's, stand up to anything from brands L or M. Trucks were always a bit of a weak point, but I don't consider that a fatal flaw. Trucks can be replaced.