I have been an avid reader of RMweb but this thread has actually encouraged me to join and make a contribution.
Nearly 100% of posts to date have assumed that this is a RTR model, but please consider:
We know a lot of purchasers acquire models to collect and never run them.
Corgi recently moved into the Diecast non-running locomotive market
The recent success of the “Great British Locomotives” partworks.
Oxford Die-Cast have made a successful business of what they do, after Corgi’s success with Aircraft they moved into this market – why not with locomotives?
The economics seen to add up as well, the suppliers of the “Great British Locomotives” will sell you the loco and part work for 20 euros –and presumably make a profit.
So my prediction is for diecast non-running models, but having said that I would certainly purchase these if they fit the area I model, if the price is right.