I don’t think they would trade Butler for Harden. It would be a backwards move for Miami after the playoffs he had. I really don’t think this move makes sense at all. Heat have a fun team and will have some cap space to improve next year, albeit not as much as they would have had if they hadn’t extended Bam already. Still they will have enough to get someone like Oladipo, and knowing Riley he should be able to work out a deal for someone without having full space necessary anyway (like he had done with Butler).
Besides Herro has shown great potential despite being so young, they just drafted a good piece in Achiuwa, they got other project in Okpala and their scouting is amazing so they will probably pick up a few good pieces off the waivers too.
Harden is a complete change of direction for a team that just went to Finals. Pointless.
I don't think they would either but as you said in your posts, it doesn't make sense for them to trade for Harden. For me Butler alone makes it questionable because he is a ball dominant player and his mentality seems to be at odd with Harden's. After you have the cost of the trade but you already addressed it.
For me the only teams that make sense for Harden outside of Houston are bad teams and/or teams where the star is a big and not ball dominant. Maybe I'm wrong though.