Well, what would be really ridiculous is the molemen-sapping we have in RTW.

I'd prefer turnbased sapping..

I hope for more moddability in siege units - editing the "siege point" value of siege towers etc.

I also worry about using artillery in field battles. Only cannon would work for this, and their role would be mostly that of depraving enemy morale. The killfactor would still be low until the advent of canister shot or bomb shot.