For the wiki, a compressed and optimized version of wanted pofs' geometry could be stored, I think this would have a reasonable storage footprint, the down side is as the viewer was upgraded and new vertex formats were needed every model would have to be re-uploaded, but that is more or less a finite hassle.
As for the forum embedded viewer it would have a storage/performance tradeoff, technically it would not require any more permanent storage than is used currently. the server side script could download the pof/zip to a temporary folder then send off the geometry and then delete the temporary file, this would however be a bandwidth sink, however if it was done on the fly and it cached it's results (and the cache was cleaned periodically (and lets not forget browser caching) ) I think it would have an acceptable resource usage.
also keep in mind there are javascript implementations of many compression algorithms, this could help on both storage, processing, and transmission of geometry.