Does icewine improve with age or does it have an estimated shelf life?
That’s essentially a two-part question. My answers: no and sort of.
Icewine, Canada’s specialty dessert wine, generally does not improve with age. At least that’s my opinion. That said, there’s no need to fret much about a forgotten bottle in your cellar. Ten or 12 years won’t do much harm, if any.
I’ve addressed the topic before (you’re not the first to ask this relevant question) and I remain convinced that icewine is one of those exception wines. Just because it does not improve with age does not mean it will degrade sharply with moderate time in the cellar.
As you may know, it is an extremely sweet beverage, thick with natural grape sugar. That sugar acts as a preservative. And, of course, there’s alcohol and acidity in the bottle, too, which fend off bacteria. But for some reason icewine lacks the je ne sais quoi of, say, great Sauternes, a sweet white wine from Bordeaux famous for developing magical aromas and flavours with many decades in bottle. Sauternes is made in a different manner, with fungus-infected grapes rather than with grapes that have frozen on the vine. This no doubt has much to do with the difference.
If icewine were that sort of wine that did improve greatly with age, it almost certainly would have found a much wider following among wealthy collectors, the way such famous Sauternes as Château d’Yquem have. The auction market usually doesn’t lie.