You can't run steam for ever. You cant run the same locomotives when they turn 150 or 200 years old. Not when they are run as hard as they do everyday. They just can't. Yes boilers can be replaced, so can nearly all the accessories, frames, wheels, ect. But you will reach a point where it doesn't make sense to rebuild it. I believe the D&S has a pattern for cylinders. That's great, if you can find a foundry willing to pour it.
When I was a kid I thought big main line steam locos would always be running, or would never be retired again. Well that is a lovely utopian though from and ignorant kid. Reality is, maintenance costs, parts availability, funding, volunteers, public interest, and the big one insurance are all things that can kill a steam program. When was the last time you saw 1522, 819,1218,614, a Reading 2100, run? When will 611 run again?
I think Randy was meant decades from now, long after we are gone. The 28s and 36 will be out of service. Other 37s might came back, or they will purchase something completely unrelated to CO NG, or new steam. But bottom line many many years away. Not in the next 20.
Jeff Taylor
CRRM curator of equipment and rolling stock.