You also won't see as many people identifying themselves as sissies in my generation, you are going to see people coming out as trans or being “femboys”, they want to celebrate their femininity rather then be humiliated as emasculated, failed men.
In my time, some decades ago let's say, I really wasn't aware of sexual choices like being a sissy or such. It just didn't seem to show up in the books or magazines I read or in imagery that I found.
Perhaps it just wasn't something that people liked to mention. After all, I am talking about the time when being openly gay or lesbian was already considered very audacious and bold.
Anyway, now it appears that some commentators, sexual researchers and such, surmise that the present-day, relatively increased incidence of men expressing their femininity is due to the influence of female liberation/female empowerment in which some men appear to willingly submit to situations of subjugation to females. In previous eras this might have been described as a variation of masochism.
I do now see a much greater incidence of imagery of sissies, trans, fembois and more and more when placed in a chastity device of some sort.
Perhaps ultimately, the choice of terms like sissy, trans, femboi etc is a question of semantics, like homosexual being replaced by gay or all the confusing discussions of correct LGBT nomenclature.