An easier question would be “what’s NOT next”. A society that allows a perversion of this magnitutde is obviously one that rejects any notion of moral absolutes. In the absence of those limits, what behavior would it NOT tolerate?
The phrase “because it’s wrong” will lose all relevance.
Once intercourse is intentionally split off from fertility, and thus deliberately alienated from its species-normal purpose and its male-female generative power, there is no reason why sex should be only for the married, only in a "committed relationship," only for two faithful partners, or only for man-woman pairings.
It was contraception that set the stage for every other deviation of sexuality from its natural meaning and its in-depth ramifications. The extremely widespread, socially-approved use of the Pill, in particular, dramatically pushed sexual intercourse toward being insignificant and inconsequential. No particular significance. No particular consequences.
Everything else followed.