Potentially, that's a deal that makes both teams better for reasons others have already addressed. Particularly, I like the trade because maybe it makes you a little more confident in IT's longevity. He's done an admirable job as The Man in this offense, but the dude hits the ground hard every single game. That adds up. Maybe the addition of Thompson can save him some wear and tear.
Two concerns that I have:
Bradley is still improving. He appears to have made a large leap in the offseason. I'm not talking about the 3P%, which will regulate. Short sample size still applies here, but he looks to be a better ballhandler and passer this season, and he has shown some shots in the paint that I didn't think he had in his arsenal. He is also attacking the glass. How much of this is real, and how much is a just a three-game stretch of good play? We'll find out. But there's a chance now that the gap between Bradley and Thompson has narrowed considerably. Counterpoint: this might also be the thing that makes GS consider the deal.
Thompson has never been The Man for any extended period before. Does he maintain his terrific .46/.43/.87 shooting percentages from the last two seasons when he's the most dangerous guy on the court? If those dip as a result of increased responsibility and defensive attention, he's not a guy who will frequently make up for it by getting to the line the way IT does.
One concern that I don't have:
Klay Thompson is fine this season, guys. He's only taking a shot per game less than last season, and all of his rate stats are roughly in line with his last two seasons. I don't think he's the odd man out at all. The glaring anomaly on his stat sheet is that he's shooting 3-28 (!) from three on the year. Think that continues? Neither do I. As soon as that self-corrects, he'll be the same Klay Thompson he's been for the last few years.
I'd absolutely do this deal if it were available, and props to the OP for coming up with an idea that I think GS at least thinks about.