(re: Solution to old copyrights)
Releasing the studio’s wouldn’t have the games be free unless Sierra said so specificaly.
I know id software gives away the source code for their older engines (Wolfenstein, Doom, Quake) but they also specificaly say that Quake is copyrighted by id and that you can’t use any of their artwork, which means you must build the game from scratch.
It would be awome if sierra gave away the engine code for the later KQ, SQ, or LSL games, but they won’t. They would say they woudn’t make any money of adventure games if that decided to re-make the games (silly idea, but true.)