Don't you think Teague has reached his peak as a Hawk, though? Pretty much gotten all that they will get out of him if you can trade him for a younger player who also fills a major need, then I think you got to do that. A front court of Noel/Horford/Sap is dynamite and would really allow Sap to open up his game. Recall how many blocks just those two (Sap/Al) had in the playoffs this year, then add Noel to that mix. I disagree with your assessment of him as a "rotational" guy, though, the kid has started 133 of the 142 total NBA games he's ever played.
Sidenote: I've watched Noel mature as a player pretty closely, and he's just really getting started to showcase what he can do at the pro level. I think that in a system like Bud's, he would actually mature as a player. Remember, for his entire career all he's ever known is a losing culture. He could potentially turn into an entirely different player. And he's still mad young.(I wouldn't say I "know him", but he'd recognize my face and say "whattup " when I'd see him in Center City. I worked at Two Liberty and almost all the Sixers players live there. Used to see the homie Thad Young all the time, too, before him and his wiz moved out on Conshohocken. Thad is mad cool, one of the coolest NBA players there is. Iggy used to live there, too...hell, Cole Hames had the entire penthouse top floor before he got married and had a kid and moved out. That jawn was laid).