Needless to say, at some point I will be taking Megas down a peg or two in a multiplayer campaign

That said, there were alot of us that enjoyed RTW and MTW2 and still play them.

While empire does alot new, government is new, ai is new, new units, new land battles, new trade, and new city set up. Alot has also remained the same. Such as the exact same diplomacy options as before. Routing in battle as before. Movement on landmap as before. (Though now you can recruit in the field.)

I think it will be different, but to say Empire will be 100% different compared to MTW2 would be silly. It's still the same series, the same ideas, the same turn based gameplay. It's just lots of new features.