I doubt it. N became popular because you can get 'more' real estate into the same house space than you can in H0 (or the same into less). Z is taking off for basically the same reason. Although that might have been true when first invented TT does not fulfill that criteria any more. It is a nice size (as is S) but I think it is simply too close to existing major scales to grab enough market share. (I remember the original TT many years ago, and also the appearance of N shortly after. I always assumed N killed TT.) So I can't see TT becoming a major scale except at the expense of pulling modellers from N and H0/00. Not many people can afford the money and space to keep two scales running, and I think those that do generally have a bigger size difference, such as H0 and N, or H0 and G/#1.