Something to consider with the Durant trade was how many more seasons of fading out in the playoffs were the Suns willing to take? I know that they fizzled again after the trade, but that is kind of immaterial. It's obvious that the Durant trade was made (for good or bad) in an attempt to evince another disappointing ending to the season. And I am relatively certain that standing pat with the same roster would have had the same result.
Now I am not saying the deal they made for Durant is above criticism. Trading all the draft choices, for example, seems on the face of it potentially egregious. But I get why Ishbia felt like they had to do something to shake things up. The team as it had been configured was never going to win, and seemed destined to only get further from that objective over time. Whether that was due to Paul hitting the wall, Monty's post season incompetence, Ayton's disappearing act, or some combination of all three (most likely), continuing with the same roster was a failing proposition.
And I don't believe little bits of tinkering, like trading for some extra supporting bench help or something similar that I see people suggesting would have made a bit of difference. Any deal they made that would have actually improved the team would have had to be for top tier talent... and that meant at a minimum, moving Bridges because he was the only piece they have that could potentially bring a difference maker in return. And for a real difference maker, that likely meant moving Johnson, as well. So it really is academic to lament losing one or both of them, in my mind.
Again, I'm not wholesale defending the trade they ended up making because they probably did give up too much with the included draft picks. But I really don't see any way they could have avoided trading Bridges and/or Johnson and actually improved their championship chances.