I have a feeling some of the people commenting haven't been following Bracket Matrix daily since early January like me :-) Your feel for this is off.
http://www.bracketmatrix.com/
Houston is probably a 3 seed as of right now, and they're probably closer to a 4 than a 2.
When Zion comes back, Duke has more room for error for a 1 seed than what some of you guys are saying. Remember, we swept the overall #1 seed UVA, and we blew out one of the other contenders for a #1 seed, Kentucky. Those wins will count for a lot, and our losses (besides Gonzaga) have come at less than full strength. Just on a practical level, think of the poor #1 seed that has to deal with Duke as their 2 seed when Zion comes back; the committee will be loathe to put anyone in that position.
As of today, Duke is probably the overall #2 (i.e. second-highest 1-seed) behind UVA, and if the committee knew with 100% certainty that Zion is back, I wouldn't be surprised if they still put us ahead of the team we swept if Selection Sunday were today.