[steam for ever]

Well Rassy in the future we know we are going to get all sorts of rail tours.
50 years ago steam specials were all the rage and still are but steam has joined the ranks.
A tour operator such as west coast railways may buy one in the future for mainline tours but that won't be for a long time. The reason being that they are still everywhere. With the electrification of the GW main line (of which I am opposed to entierly and would go for hydrogen powered trains) the vast majority will be withdrawn. Virgin started it and this will most likely finnish the job.

We cannot be certain but my advice to you is to enjoy them while you still can. I do know of several people wanting to start preserving mark 3 stock and this I think would be a good idea but something tells me they will outlive the units that haul them as they are transferrable to the 225 units.

Pete Waterman is very rich and he has a passion for steam and so does David Shepard but with a bit of persuasion they might consider a one off diesel venture to save one of the most important modern traction sets.
Hope this helps put your mind at rest.