I was driving around with my dad the other day, and the Bee Gees came on the radio. He turned sixty back in March, so he was in his late teens when disco started breaking into the mainstream, and his early twenties when it crested and then crashed. He was a huge fan of disco both then and now, and one of his favorite satellite radio stations is the disco station; he may be a straight Irish-American man, the sort of demographic that supposedly hated disco, but he was also a New Yorker who grew up around the clubs.
I'm bringing this up because something he said reminded me of every complaint that's ever been raised against music genres that got "too popular". In short, he viewed Saturday Night Fever, and not Disco Demolition Night, as the moment when disco died, as it not only supercharged the genre's popularity, but it did so by painting a very inaccurate picture of it. (I informed him that the article it was based on drew more from British mod culture than anything found in the actual clubs of New York and Philadelphia, and he was not surprised in the slightest to learn that.) At the same time that Middle America was turning against disco, viewing it as effete and alien to what they knew, the genre's original fans, the people who frequented the nightclubs, viewed the wave of disco rising in the mainstream as a sellout that had barely anything to do with what they saw as real disco music. This, I feel, helped fuel the rise of punk rock, with many fans who viewed disco as having grown shallow turning to punk. (They'd never admit it in a million years, of course.) To prove his point, my dad played me a selection of some of his favorite disco songs, which very much weren't on the pop end of the spectrum; I can't remember the titles or the artists (except for "Your Love" by Lime), but they were a world apart from the pop-disco that was big on the radio at the time (and on oldies stations these days now that it's socially acceptable again). You can see the same thing happening now with EDM, with the divide between pop-friendly DJs like David Guetta and Calvin Harris on one side and what actually gets played in clubs on the other.
With this in mind, I think the best way to keep disco surviving into the '80s (in forms that weren't shy about their inspiration) would be, ironically, to prevent its explosion in the late '70s. Without Saturday Night Fever, disco probably continues on a more stable trajectory, probably peaking around 1979/80 before fading away in the early '80s. You'd get backlash, sure, but without such massive overexposure, you likely wouldn't see the whole country suddenly turning against it overnight.