Iam afraid-or know for nearly sure, that such a wonder will not happen. Der Chr himself has told many times he will not visit sauna in BKK again (and I agree-much better the few in provincial cities).
I have read a week or 2-3 ago some other report in another forum (worldwide, used to be good on TH-but that was many yrs ago) someone visited one in suburban BKk (way far from Silom)-this has halved in size and ´crowd (I never really encountered big crowds when I went to sauna-many yrs ago) also halved.
That chain that discriminates farang-and even more elder-by charging them doubled/5-fold entry prices seems to be doing well-seeing their ads etc on Thai sites and some reviews. That probably sums it up..........