Hey guys -
I didn't mean the 3,000 foot figure literally necessarily; it's just a shorthand way of saying 'up high.'
I would agree that brook trout are expanding their range. When you consider that all of the Smokies and most of the other forests in this region were basically clear cut by the 1920s, and then think about how slow trees grow (and really how immature even the trees in the Park are to this day), it stands to reason that as the forest returns so will the trout.
Barring any big political changes I think the Smokies will have returned to a primeval state some time by around 2200. I really hope my great grandchildren get to experience brook trout fishing like there once was. I also really appreciate the NPS for furthering that goal.