As a Corrado VR6 Storm owner, I don't think they'll ever attain "Classic" status. They simply weren't thought of highly enough when new, and never really pushed the boundaries. They were good, without being great. The fact they were also stupidly expensive, and released when the last recession was the buzz word and fuel prices were uber high at the time, mean't they didn't sell well. An awful lot of parts are also obsolete now and very hard to get hold of. Some are available from VW Classic parts, but they are usually stupidly expensive. Prices are rock bottom at the moment and will rise a little no doubt, but I wouldn't bank on it being a lucrative investment for the future. Don't get me wrong, I absolutely adore it, and you won't find a better FWD handling car of that era. They have amazing character too and are an absolute joy to drive. A small cult following will be as good as its ever likely to get though unfortunately.
Rocco or Mk2 Golf Valver would be my recommendation tbh.