There are so many "what if" and "why didn't they" situations.
Why didn't SP preserve 4-8-4 4458 or 4459 - the roller-bearing-equipped units - say one in LA and one in Oakland or Fresno?
Why didn't UP preserve a 4-8-4 in Southern CA, or another Challenger?
Why didn't NP preserve an A-4 or A-5 4-8-4 in Minneapolis?
What if NYC had preserved one each of their "Big Three" - a J3a Hudson, an L4b Mohawk and a Niagara?
What if GN had preserved an R-2 2-8-8-2, or Southern a couple more PS-4 Pacifics, or MILW an F-7 4-6-4 Baltic or CNW a 4-8-4 Zeppelin?
What if IC had preserved 4-8-2 2613?
I am sure everyone can add to the list.
The sad thing is saving those locomotives would not even have moved the needle on the carrier's bottom line in the year they were scrapped.
Thankfully UP 9000 is around in Southern CA and SP 4460 is around in St. Louis and many others are out there, far from home rails but at least still around.
But indeed - What if????