Enough with the harden love. That’s like taking back a cheating ex knowing she’s going to cheat again if that’s what you into then all power to you but no to frauden
He'd actually be great for Sengun. FVV and Sengun ran an above average PnR for a long time. Harden would be much better at that than FVV. So we'd have that down. KD will get his shots, we've seen them in Brooklyn. It's Amen who will be marginalized and wonder wtf we're doing with his career. If I see myself as a star and the league's GMs see me as the most likely breakout star in the NBA and my coach keeps pigeon holing me into a swiss army knife type player - at some point I'm going to want to join one of those GM's who has a higher belief in me. Amen is the most valuable asset we own, period. He's the only asset that can give us a rare historically elite ability on 50% of the court (defense). Even KD only impacts scoring, he's not giving you historically elite overall offense on half the court (too low in assists). We don't have a player or a pick we would value over Amen. To keep marginalizing him is a bad idea, especially since his extension is coming up. Another guy who needs the ball in his hands just to not be negative = horrible idea.
I think it would require a significant haul of assets, perhaps more than we gave up for KD (assuming you valued Jalen as basically getting paid fairly or even being a bad contract). I also think our defense would be below-average starting Harden and KD together. And, as @Mathloom said, it would limit opportunities for Amen. I don't think it really makes sense at this moment in time. What I would support would be him coming back for a farewell tour in 2027 after his current contract is over. Off the bench, as a 6th man.
You'd have to send end-of-our-bench players to do a titty-bar crawl to find him. "Hey, aren't you on the Rockets? Yeah, Harden's back in the Stain Room. Up to you if you want to go in there."