My impression has always been that drinking aged whisky was more about signalling (both financial status and knowledge and taste), including in the largest markets (France, etc.). Same reason people still wear suits and Goodyear-welted leather shoes for work. So there'll always be a large demand for aged stuff. If you just want to get drunk, vodka is better for hangovers and a lot cheaper. For example, a liquor trader here told me Indonesia is really into Chivas 18 year old, which is by far his largest export there.

That being said, economics have made it happen already: there have been no age statements on the "basic" offering from all mass market Japanese single malts (Yamazaki, Yoichi, Taketsuru...) for a few years now because the vastly increased demand effectively emptied the stock of the 10-12 year old stuff that was previously the default. I also get the feeling that a lot of Scottish houses are cutting their product with stuff that meets the age requirement for labelling but is not as good as what their products were made of 10-15 years ago.

In terms of taste, I think the "fast aged" stuff is a different product. Younger whiskies have a very different flavour profile (not necessarily inferior - try a Port Charlotte PC5-7). Can it become a new market segment, certainly - in fact it already has (e.g. Laphroaig Quarter Cask mentioned elsewhere in this thread). Replace, I'm less sure.