I think it won't just disappear in a year: the Laphroaig 30 was like that as well. In fact, the L30 pretty much kicked around for a couple of years at $225 - $275 USD while it was starting to sell for 200 - 400 pounds
in the UK and Europe before people started snapping up all the remaining bottles...
I don't expect the 15yo to command anywhere near those prices, but it will probably slowly be consumed and then - all of a sudden - will be mostly gone.
Whether it's value increases or not - I just saw a Laphroaig 30 on sale for $599 in Las Vegas, ouch!!! - remains to be seen, but I don't think that it can demand the high dollars that the 30yo seems to.
That being said, I really like the L15 and have a few of them stashed away for the future