Both new executives, Vinnie James and Adam Miller, previously worked under Patrick Kraft at Boston College and Temple.
With a UFC roster spot possibly at stake, Nickal will fight Zachary Borrego on August 9.
"USC and UCLA are both synonymous with academic and athletics success and will be tremendous additions to our conference."
USC and UCLA will become the Big Ten's 15th and 16th teams beginning in 2024.
Mack will join high school teammate Conrad Hussey in Happy Valley, who committed to the Nittany Lions' Class of 2023 in April.
The Squirrel and Acorn Bookshop will replace The Animal Kingdom later this summer.