Depending on the Air Force conference situation, Texas and a few others could try to drum up a men's lacrosse league under the MPSF banner. Of course, given that any new men's programs likely will be at schools also adding women's programs, the next lacrosse conference could be the Big XII.
Texas would also need to find an ESPN-friendly league to be able to keep feeding the LHN. That automatically cuts out the Big Ten.
If Texas adds lacrosse, I think the Big East would be where they end up unless they go independent. They took Florida and Vanderbilt as affiliates for women's lax, and with Denver nearby it would make travel that way easier.