I vote yes, and I'd pay up to $10 for the DLC or up to $20 for a more fully fledged MP expansion of sorts. HotSeat, PBEM, LAN, Internet, Co-Op vs AI, PVP? Hell yeah to any of it! I welcome playing a great video game with others as opposed to alone - be it FPS, RTS, RPG and TBS. The more the merrier!
Does it have to have the same great game play as the SP? Yes it should be there (and of course be save-able over multiple sessions like SoaSE).
I believe it will also need to have quick pre-sets or game modes to choose from, accommodating online matches lasting approximately 30-60-90 minutes. Is that possible to do? It probably can be done in multiple ways (count-down timer, smaller maps, less AI players, game speed 'faster', tactical only battles, grab certain non-faction AI areas to get a large effect that enhances your army etc...). Will that change the flavor of the game and make people call me a blasphemer? Yeah, probably. But then again, they can go back to playing SP, or MP with the 'original' format. You want to bring as many people into this (now very niche) genre as possible in order to keep it going. Doing this and having available MP mods could do it.
PS: I would buy the MP DLC - of course - only after making sure that all those single player gamers out there are happy with the existing SP game. We wouldn't want them to point the finger at using precious resources for MP DLC for the reason why SP isn't exactly they way they'd expected it to turn out...
On second thought, that's untrue. I would buy the MP DLC no matter what, seeing as how you've (Stardock) already used precious resources to give your single player TBS gaming base a second game for free. No one should be complaining now, should they? Thank You guys, for all the hard work you do.