These conversations are SPOILERTASTIC, so if you haven't watched the ep yet, be forewarned.
So, not much was answered last night. The whole thing about stuff going south for Sayid was something that could have been easily guessed given what happened to Ben. The revelation about Claire was a little something, although we've known for some time that she's been working with the Esau/Smoke Monster to manipulate Locke.
On the "what if?" side of things, I found the circumstances surrounding Kate and Claire very interesting. Far more interesting to me was the appearance of Ethan as the doctor who first sees Claire. This doesn't jibe with pre-established events. We've already seen that Ethan was on the island when the plane crashed and was sent to post as one of the survivors. So, if in the "what if?" timeline he's not on the island and at the hospital, a heck of a lot more than just the passengers' histories have changed.
I guess we have to have some well-established set up for the finale, but I still don't feel any closer to having any answers.