So I'll pose this: Will mods to modern drums hurt their value 30 years from now? I don't think so, because I don't see too many modern drums (those without any special provenance) attaining any kind of collectability status, any more than a new Honda Accord becoming collectable 30 years from now.
Maybe they might. Here's my opinion ....
As the 50's and 60's drums get more scarce/non-existent, the 70's and 80's drums are going to be the next craze. We are starting to see it more now with the mid to late 70's Rogers Big R drums. They get a bad wrap, but they are still the 5-ply re-ringed shells that sing. Heck, just look at the increased interest in MIJ drums. Look at all of the times we see a posting about someone's latest Star kit purchase for sub-$100.
Plus, as the drummer population shifts generations, there will also be a shift in what is "vintage". This will have an affect on the interest in older drums. Just think of the quote "I'm looking for a
-Tim