I wouldn't be surprised to see the Super Redhawk Alaskan show up in .44 mag, which might have broader appeal than .480 and .454 given that the Redhawk cylinder can handle standard factory .44 ammunition all they way up to the super-long, super-heavy premium loads. I know I'd be interested in one.
This past spring, a Ruger guy (factory engineer, not sales rep) told me that the materials and machining of the SRH are completely different from the materials and machining of the SBH. In other words, it would take more than simply chambering the existing SBH in .480 or .454 to override their safety concerns.
But if they are completely re-tooling and re-designing a new, heavy frame single action ... it could be interesting.
Blunderbus