There are 7 guys who worked the regional level in both 2016 and 2017 but have yet to work this years regional with only the Kansas-Duke game remaining:

Doug Sirmons
Gene Steretore
John Higgins
LaMar Simpson
Roger Ayers
Ted Valentine
Tim Clougherty

LaMar is retired or injured I think. Valentine is out. I have it on decent authority that Higgins is out. So that leaves some 3 man combination of Ayers, Sirmons, Steretore, and Clougherty to work Kansas-Duke, barring a surprise.

I'm guessing Clougherty will miss out and Sirmons, Ayers, and Steretore will work in about an hour.