The other way of looking at this is that the nostalgic link will keep moving and be focused on the diesel/electric traction of later years and that if people model steam then it will take the form of a heritage line. Of course, if this were true then I should want to model the BR blue/grey period but I have no nostaligic feel for that, though I am sure there are some that do. As it is I do want to model a pre-grouping railway, in my case the G&SWR, but I suspect that is because I have always loved history in the broadest sense and have taken that same interest in the historical into my love of railways.
Although there are more pre-grouping models I suspect that we are not on the verge of a golden age of pre-grouping though because to do it properly will (almost certainly) always require kit- or scratch-building which puts most people off. I know how they feel because I am approaching the whole idea of kit building with great fear and trepidation. My children keep on asking why I haven't started building the stock yet and I am running out of excuses, so who knows.