I had a feeling that it would end after Season 4 or Season 5, and it looks like it'll be sooner rather than later. Oh well. I think it's perfectly right for them to end it and wrap up the story conclusively. They could drag it out for a long time, but with the story revolving around a search for a particular place, you have to end it sometime or start churning out crappy filler plots. I think the second half of Season 2 was pretty eh, but Season 3 was absolutely top-notch. Especially the finale. Probably my favorite episode of the entire show, in fact. Good news, I'd say.