Yea Noel could learn a ton from Pop and honestly I think he would be much more of an offensive threat in the Spurs offense.
As for Aldridge, I'm a little tired of him and he's been pretty disappointing with the Spurs so far. I don't think they'll move him prior to the season because his value is at an all-time low right now after the way he's performed in the playoffs. The Spurs are not ones to "blow it up" so I doubt they move Aldridge unless they can get a contributor or two in return.
It was sad to see Simmons go and who knows how he will do in Orlando when he becomes a starter. Part of the reason Simmons was great was the system around him and the guys he was playing with. It's something we see time and time again where players will get moved from the Spurs and then do basically nothing. Just look at Gary Neal, Marco Belinelli, Boris Diaw (traded, but same argument applies), Tiago Splitter (also a trade). The Spurs system is part of what makes those players more than just role players.
Do you really think he'll be an offensive threat? That's a little surprising. I always thought he was much better on defence than offence. He's good at catching lobs around the rim and has a decent touch but he doesn't have much of a jumper.
And I totally agree with your second point. The Spurs system is what makes those players great. Even Cory Joseph when he came to my Raptors I thought would contribute more but as you probably know we've shipped him off to Indiana and have basically promoted Delon Wright to permanent backup PG.
Maybe the term "threat" is a bit of a stretch, but I think he can be a Tiago Splitter type of guy. Doesn't dominate on the offensive end, but can get you a sneaky 12-16 points a game.
And yes Cory Joseph is another great example!