An idea I've always had for something like this is to have a system where if someone enters my territory, I get an e-mail or a text about it, so I can get back home and try to set up some sort of counter offensive before they get to do any real damage.
It would be nice to have some sort of hardcore option where in this would be the case. Your lands are up for taking if you are away, and whatever automated defenses you have (defending armies and NPC's) kick on to take up whatever defensive options you've left them until you return.
Perhaps, when you log back in, your hero avatar could help swing the battle back to your favor as you take full control over your defending armies?
Thats a dream. Getting a text/e-mail while out picking up groceries, rushing home to defend my land. That would be intense.