Four, actually; they're doubling up tomorrow and next Monday. I'll be interested to see if this bumps up the ratings by turning both weeks into "event" viewing, or simply burns off the remainder of the season. The ratings seem to have reached a stable level across the season (the bump for "J.R.'s Masterpiece" not withstanding), and are higher than freshman follow-on Monday Mornings.
One final thought about whether or not Pam is going to reappear: if Victoria Principal does come back, I really hope they have the good sense not to list her in the guest stars at the beginning of the episode. They did that with Ken Kercheval in last season's finale, and it totally spoiled the big reveal on who Pamela/Rebecca really is by virtue of him not having appeared in the entire episode, yet he was listed in the guest cast. As soon as the hatch opened on that plane, I knew Cliff was going to be the one to step off.