All it is going to take is for one example of the "superteam" concept to fail on a major level, and everyone will drop it. No franchise wants to be paying hundreds of millions in luxury tax for a team that isn't bringing home a guaranteed championship. It could be as soon as this year if the GSW fall on their faces, which is entirely possible once the over expectations, chemistry issues, complacency, and other "human elements" naturally set in. Nothing is won on on paper.
In any case, sports run on a reactive and imitative basis. One team being successful at something inevitably starts a trend that everyone else jumps on (as much possible) until it falters... then it's on to the next thing. Baseball is a good example - for decades everyone followed the NYY model of throwing massive money at any and all high priced free agents. As time went on, lots of teams found themselves stuck with high payrolls and nothing to show for it ("Los Angeles of Anaheim"... ahem), and the teams that actually started being genuinely successful began building from the ground up and investing more resources in youth, scouting, player development. And now, what do you know, but nearly every MLB franchise is doing that - even traditional high spenders like the Yankees. The other approach just wasn't sustainable and became downright stupid.
So all the Suns really have to do is stay the course - the "superteam" fad will run it's course, eventually ending in some kind of crisis for the teams that are following it. I fully expect the Warriors to end up as a wreck of a franchise sooner than anyone else seems to be expecting - there is a certain inevitability to it. Yes, they will have their four or so championships to look back on, but that is more a result of dumb luck than brilliant planning. The Superteam Heat have their two championships to look back on, but it may not be much solace for a fanbase that is now stuck with a team in perpetual mediocrity purgatory.