Res has seen a very steep decline in enrollment in the last decade. With the Christian Brothers taking over Res, I view it as a long term possible plan to move Pat's up to the Norwood Park/Edison Park campus probably to become a Co-Ed school. I believe Pat's plays some sports there and I am sure that they would LOVE to put a football/baseball/soccer complex there as well
If they become a coed school on one campus, then they will compete on the northside in the Catholic coed space with Ignatius, Fenwick, Loyola, DePaul, Guerin, Holy Trinity, Viator, etc. Not sure that is the right move for them. Right now, they have the all-boys space on the northside of Chicago to themselves, although they do share that space with NDCP in Niles, which draws students substantially from the north and northwest sides of the city...along with Pat's.
More likely, I see Pat's eventually doing what their sponsoring Lasallian Christian Brothers did with Lourdes by becoming a single coed school with two single gender campuses. This would allow them to achieve some economies of scale while maintaining a large part of the single gender character and traditions of both schools. They could do that and still put in the sports complex you talk about. However, I think it is important to bear in mind that all that land that Res sits on (plus the open land east of there along Talcott) belongs to the Res Sisters. I don't believe we know what the ownership disposition of that land is relative to this agreement to change the sponsorship of Res from the sisters to the brothers.
I think the recent decline in enrollment at Res has been due, in part, to ongoing turnover and problems within the educational leadership levels of the school. If the brothers can settle that down, then perhaps that enrollment decline can be turned around.