This has already been happening but is likely to increase by 2028.
Femcel is really the wrong term for this. Very few females under menopause age lack sex. What women tend to lack is committed sex.
Chateau Heartiste had a term for these women. Insols - involuntary solitude.
The female insol and the male incel are roughly analogous. However, the female insol is rarely a social outcast and usually has acceptable social skills. She has some female friends and usually fits in somewhat well in social situations. This doesn't happen with male incels. The female insol is able to get sex if she's under menopause age.
Its interesting because I was having a glass of wine with a female friend of mine last night who is easily a 6/7 and she has pretty much renounced herself to becoming a Female Incel at 33
Not because she can't attract any men but seemingly she can't attract a man that mentally or emotionally stimulates or excites her enough so she just disqualifies
She's a chronic app user and reports mostly dead ends much like most of my male friends that still use the apps
Theres extreme disillusionment between single men and women and I think it comes back to each sex not being able to see beyond their own needs
Men seem to want immediate sexy time and X rated porn show behaviour pretty much from the word go
Women want a guy who's going to sit and listen to her and open up with her ...physcial sex is a much lower priority
You can see the friction these opposite needs are causing and swipe apps have completely laid them bare