In an interview with Gamerzines, Turbine talked about the future of the Lord of the Rings: Online after Siege of Mirkwood launches this fall. Volume 3 will start with a free expansion coming out in early 2010.
Adam Mersky, PR Manager at Turbine told us: “Volume III will kick off with our first content update of 2010. With our expansion this year we’ve changed the model; you can still expect to receive regular (free) content updates, but they may not map directly to the launch of a new Epic Story. The story will progress and proceed!”
It was also confirmed the Riders of Rohan would be coming, but not necessarily be the name of Volume 3.
It will be interesting to see where LotRO will go in the future. There is a lot of much requested updates, namely mounted combat and a new PvMP region.

Comments:
Ilaras of The Dunedain:
Sweet. Now that I have tried the trial I am hooked. Looking forward to it!:)
Samus1111111:
good for you Ilaras :P
I hope that Riders of Rohan is the next release, but if not, oh well, all the releases are good :D