I suspect the requirements of the whisky industry for peat are probably pretty tiny - as far as I know its only the smaller higher end distillers that actually burn peat.
Peated whisky is a specialty product, with rather small production scales compared to unpeated Highland and Speyside malts. So yes, it is quite sustainable, given the regrowth rate.
Many years ago when I was a student I had a summer job working in one of the huge industrial scale maltings that supplied quite a few of the popular whisky brands - I can't remember if they produced peated malt but I do remember their analysis lab having gas chromatography equipment for analysing such things.