Tubes aren't going anywhere as long as the manufacturing facilities and tooling remain in Russia and China where Economics 101 doesn't come into play. It's more about being able to do something the rest of the world can't and with a low paid work force, they can do it. As long as someone doesn't bomb the plants like they did in eastern Europe, they will be around. Once the tooling is gone though, the end would be near. Tube pricing has remained stable the last decade while everything around it has gone up. If anything, they need to jack the prices up slightly to maintain the art of tube manufacturing. If it goes tits up, I still have a big stash of glass.....
