It wouldn't remotely surprise me if we don't see a lot of late 90's to mid 2000's vehicles getting run and rebuilt for a long time, kind of like Cuba. Barring perhaps the crashworthiness, for areas with no rust, it's kind of amazing to see how many older GM trucks of that era are still running down the road (I know I've got a couple myself).
It's hard to imagine ponying up many tens of thousands of dollars for a new truck, when they don't really do anything better (or are often worse) than what you have, and the cost of overhauling an older truck still comes out pretty favorably. I wonder if GM is cursing how easy and well understood it is to rebuild and improve a 4L60E or a small block chevy?