If they can pull it off - fine, but most supergroups are relatively short lived, due to a clash of egos. The only exception I know of, that lasted long term, was Emerson, Lake, & Palmer, but even they squabbled on occasion.
As a musician (I used to play guitar in rock bands), I can tell you from first hand experience that many musicians (moreso than the general public IMO) are flakes, who don't do the "I'm in it for the long haul, and as such, am willing to make sacrifices/concessions for the sake of the band" thing very well. They just are kind of la de da about things (a couple of bass players I played with come to mind), or (especially of they are from highly successful groups) have overblown egos, and "just know that my way of doing things is the right and only way to do things." This causes bad enough personality clashes when it's just one band member. When you end up with multiple band members having this mindset (a higher probability in supergroups), it can be downright toxic. Most supergroups implode after one or two albums, usually not living up to expectation for making great music the public expects from them (due to the clash of egos), or end up just being a "what the heck, let's collaborate, and make and album" side project for the musicians in the supergroup.
IMO a supergroup with Miles Davis, Tony Williams, and Jimi Hendrix would be cool (Paul McCartney, wouldn't fit in too well, he doesn't strike me as really being into jazz or fusion). Jimi did mention before he died, that he wanted to explore jazz, and both Miles and Tony, were great jazz players, but I wonder how long Jimi would stick to Jazz (before he died, he seemed to want to explore all genres of music in general, beyond, the blues, R&B, and rock & roll, that were what he had been mainly exposed to), before he got bored with it, and decided to move on. Also, Miles Davis was known to be an overbearing personality in his bands, and I wonder how long Jimi Hendrix would put up with that. In short, the Davis, Williams, Hendrix supergroup, featuring IMO Monk Montgomery on bass (he played bass in jazz guitar great Wes Montgomery's band for a long time [Wes was his brother], and would be a better fit than Paul McCartney [and a better bass player IMO], also he would be at loose ends after the death of his brother Wes in 1968), would probably be gone by 1972 or 73.