Fat bike sales have peaked. Everyone that wants one has purchased one. Without a fat bike I wouldn't be riding in the winter. There are still people riding fat bikes and will continue to ride them. Fat bikes aren't going anywhere and neither are the supplies for them.
You may want to upgrade to something other than a Pugsley. The tech on fat bikes moved very quickly in short span and now has settled on wider hubs for wider tires and 1x drivetrain. Surly and their steel bikes have been dying for a while. Of the people ride with and all the places that I go fat biking in the winter...I never see a Surly out there. Nobody wants them.