OK,
Now that we know the Expansion is coming, its up to Turbine to whip the playerbase into a frenzy before it arrives. Now from all indications, it appears to be at least a good 6 months from now, leaving Turbine lots of time to do this.
But why wait?
Tolero and Cordovan should each week (and make it the same day each week, so people know that they are getting a tidbit) drop us a little hint about whats coming. Heck, Fernando already said we were getting Driders, so why not a post about Driders, their origins why they should be "feared" and maybe share some concept art. As we get closer maybe even show some in game art as well. I thought this was effectively done when Lotro did its Expansion for Isenguard.
While the first few weeks (even months) might be nothing more the fluffy lore and background information it would give us something to look forward to each week and to discuss. As we get closer to the launch, then you can start hinting at actual stuff in game (because I assume the expansion beta will be NDA) and if you play your cards right, people will be ready to purchase it when it drops.