The trade is okay. As Bufalay suggested, it has the risk of being more like the O'Neal trade than like the Barkley trade. Durant is better now than O'Neal was then, but this is a highly desperate move that gambles everything on the next season and a half.
Bridges and Johnson were good citizens and valuable players, but neither is a consistent impact player. Neither will ever be more than the fourth or fifth guy on a good team. The Suns will feel their loss now more than they will in the future.
The Suns do not own their own first-round pick in the 2027, 2028, or 2029 drafts, and there's no protection. That's incredibly risky. How do the Suns expect to have a playoff team by then? Booker, Ayton, and G-leaguers? So probably the team gets completely blown up by that point, most likely including Booker, in an attempt to get some picks back. By then, though, no one will be giving up unprotected picks in those drafts, so the Suns will be trying to rebuild around lower picks at best. I can't see any way that this won't be a dismal period.
Of course it's all worth it if they win the title this year or next. But how likely is that? None of the four stars can stay healthy. Furthermore, none is an above-average defender, so even in the one game every six weeks when they're all able to take the floor, they're going to give up 140 points. This trade definitely raises the Suns' ceiling for the short term, but I don't think it makes them better. Basically it's like spending $1000 on lottery tickets because you might get lucky and scratch off $10,000.
I don't blame New Guy for wanting to make a big splash, but the draft situation at the end of the decade is terrifying, and the chances of everything working out as planned are very low.
Also, Durant is a jerk. I loved Barkley even before he came to the Suns. He was a jerk too, but I always felt that his heart was in the right place, and his fire on the court was infectious. Durant is just a pouting baby whose claim to fame is that he road the coattails of a Warriors team that was championship-caliber without him. If he gets the Suns to the promised land, okay, but I'm never going to be enthusiastic about him.
