This might seem like a cop-out answer, but now's a great time for you to start wrapping up the stories you've been roleplaying for the last two years. I suspect an immense number of people are going to reroll worgen and goblins, so if you want the chance to play out story endings with your regular crew, you better take advantage of it now. If you wait too long, some of your audience will have swapped out their usual characters for the green skin or furry crowd.
We have at least a few more months before Cataclysm hits the floor, of course. So you don't have to rush to wrap up your epic sage this week or next week, but you should start the slow and inexorable denouement towards climax. While we obviously don't have any solid notion of when the expansion will be released, I'd still try and make sure your stories are done in the next three months. We've got the Ruby Sanctum and other pre-expansion world events coming up, and you're going to want to take every opportunity to fully savor those events.
This is also a good time to start exploring other parts of the game. The Icecrown Citadel buff is now at 15%, which means more PUGs than ever before are getting the chance to throw down against the Lich King's legions. If you've not been an active raider, take the time to gather some frost emblems from heroics and see if you can't get inside the raid. Don't worry so much about things like GearScore and that crap; just put in a bunch of good-faith effort to improve your gear, and see if you can't eventually grab a PUG. It'll happen eventually.
Of course, if you do manage to grab a raid, don't be afraid to roleplay a little while you're there. Focus on the raid and make that your number one priority, of course, but don't completely ignore your RP nature. In between pulls, take a moment and throw out a little emote here or there. Maybe talk a little in raid chat in character, if you think that's appropriate to the group. The idea is that while you're expanding into raiding life, maybe you can expose them to a little bit of the roleplay life.
Alternatively, maybe you could try out some PvP. Oddly, PvP always seems to be the least likely playstyle for a lot of roleplayers. Maybe because when you're in the middle of player versus player battle, it's an awfully bad time to try and get your in-character groove on. Maybe it's because a few hundred arena deaths breaks a little bit of the escapism.
Still, if the game is feeling a little stale, now would be a great time to strap on your armor and go to battle for your faction. The Horde is nothing but a bunch of smelly brutes, and the Alliance certainly needs their pansy little flag kicked in. Try out some of the battlegrounds, especially if you consider your character a soldier for your faction.
Lastly, don't forget that the gnomes and trolls both have some big events coming up. The gnomes are finally going to kick some trogg tail and reopen Gnomeregan. The trolls are taking back the Echo Isles. If your character isn't already friendly with a troll or a gnome, now's a great time to get that way. Set up some personal investment in these upcoming events, so that you can have a richer and more meaningful experience.
Now, this would be a little odd if you just walk up to a troll in a bar and just said, "Hey, mon, I heard you got these islands with some kind of trouble." You're probably better drifting sideways into the friendship, so that the whole story doesn't become too obviously a setup for later content. Hit some heroics, do some PvP, grab a beer or three, and rock out.
The ultimate goal here is to try and explore other options. You can't force anyone to be online, and things are definitely going to be a little slow until more information about the expansion hits the ground. Try and do things now to prepare for it, and end your Wrath of the Lich King experience as positively as possible.
All the World's a Stage is your source for roleplaying ideas, innovations and ironies. You might wonder what it's like to sacrifice spells for the story, or to totally immerse yourself in your roleplaying, or even how to RP on a non-RP server!