If you're not going to make changes there's not much point in a new edition.
Can you name any game that went into a second edition without major changes to the system? Dungeons and Dragons didn't.?
Part of the reason to make a new edition is to blend and reorganize. When Erick wrote ADRP he hadn't put together Shadow Knight yet. Also, Zelazny hadn't written his last 5 short stories. All of this material could be brought into a 2E game.
And a 2E might bring an out of print game back into print!
Actually, D&D is very similar in most of its incarnations -- brown book OD&D, Holmes Basic, Mentzer and Modlvay versions of B/X, 1E AD&D, and 2E AD&D are all quite compatible with one another. Those changes were in terms of orgainzation, addition of material, and other minor things. From 1974 until 1999 the game was essentially the same; it wasn't until the new 3E edition in 2000 that major changes occured to the core mechanic.
Also, Tunnels & Trolls is a game which is in 7th edition, yet the first six editions of T&T were all very much the same. Again, minor tweaks but no complete overhaul.
GURPS underwent several versions and the basic system remained unchanged. Again, I'm not counting little stuff -- only major system overhaul.
So why throw out ADRP and replace it with a new game? If you want to make two games (ADRP Classic and ADRP Nobilis, for example) go for it. Just don't take away what we like.