The best option would probably to be what EA did in 2007 and have a special "Ashes" mode inside another game.
Thinking about that; its actually really good and should have been in every other Ashes game - for those who haven't played it; it gives you two scenarios from each test in the 2005 Ashes for both teams. Take that, attach it to a game engine that's actually fun to play with, perhaps make it random scenarios from other Ashes (Headingly in 1981, Edgbaston from 2005 come to mind right now, probably a bit of bodyline as well) and release it in an Ashes year...
The scenarios mode in BLC99 and BLIC05 were seriously really fun because of the nature of the scenarios; imagine how good it would be to have those in an actually good game!