I think it's interesting that it was Lois who brought up Lana and her future with Clark. Lois, the one who has already admitted to herself that she wants to try for more than five years. Not Clark, the one who is still hanging on to the countdown.
Maybe Lois was hoping Clark would say that there was no longer a countdown (if so, that was a naive hope, to say the least). Maybe she thought honest communication would make them better friends. I'm not sure what the driving force was for bringing Lana into an otherwise cozy conversation, but I think it's safe to say Lois had more emotion loaded into this question than she let us see. ("Are you and Lana planning on having kids?" I asked, not looking at him.")
My point is this:
With the tenuous peace they've achieved, neither of them are going to rock the boat. They're both going to profess to want (or at least accept) the countdown long after they really do because they will each be playing to the other's expectations. We're already seeing that with Lois.
The one who finally says, "Hey, I love you. Let's make this real," is risking a lot. I don't see that happening anytime soon.
Lisa, who wonders if Carol is going to take us right up to the five-year mark before one of them breaks. A divorce-courtroom confession of love!