One of the reasons I feel that Turbomotive is more likely to come from Hornby. They have proved that they are not afraid of producing historical one offs or loco's with only a few members ever created. The P2, W1 and Rocket are prime examples.
I personally would love an RTR Turbomotive. Probablty won't get a W1 because the version I wanted sold out in seconds but I'd be primed and ready if Turbomotive got announced. Could even include the modifications made in later life, like with Hush Hush...