Frankly, I would rather kiss goodbye to colour negatives than transparencies. Even though colour output has largely moved to hybrid process people still want to use a neg. I can see the case for portraiture/weddings I suppose, but generally reversal films just look so much better. Regarding the investment thing. Ask yourself why you take photos, and why you use film for this? Returns on investment can take many forms. The best return I get for using transparency is the feeling I get when I hold the films up to the light. I'm afraid that is something digital will never be able to replace for me.
All you can do, all anyone can do, is use it if they like it, and talk the stuff up to everyone they know. Jan has the right idea, we just need to clone a few dozens of him. 😉 Using as much as you can is no guarantee the films you like will still be available in five or ten years time, but, if usage declines much further I can sure as hell promise you, that they won't be.
Cheers
Brett