That's my thought. Riverton gets in, Brunner becomes an individual qualifier, and then the at-larges shift to other regions bc the SW will have 26 runners at that point and the next two individuals don't have incredible credentials outside of their finishes at the NXR region.
IF Niwot does get an at-large, there's absolutely no way in my mind the SW gets an at-large individual spot at all.
My current picks for at-large spots are Riverton, Austin Vandegrift, Franklin, and Plainfield South or Rocky in that order. Niwot was just so far back at their meet. While a great resume can help push you over the top as an at-large, it can't hide a terrible regional meet.
Unfortunately, Niwot doesn't even have a great resume. Their big win at the 4A state meet was over the team that got 11th at Liberty Bell. The team they dominated at Desert Twilight was 6th in the Colorado 5A state meet and 26th at NXR SW. The team that got 4th was the 10th place team at the Texas 6A state meet and got 14th at NXR South. The third place team did win the Division 1 Arizona state champs, but their runners went 8-10-18-26-30-38-46 and are 4:21/9:18, 4:27/9:39, 4:22/9:37, 4:38/10:03, 4:45/9:59, 2:09/5:02, and a 42.24 300mh/2:17 guy. Decent for 1-5, but zero depth beyond that and got 27th at NXR SW.
If you told me that a team finished 99 points out of qualifying in their NXR region in 4th place, beat one team all year prior to NXR that finished in the top 10 in their region, and one of their marquee wins were over the teams that finished in 14th, 26th, and 27th at their regions, I would say that team has zero shot of being an at-large.
Once California runs, Rocky and Plainfield South will get pushed out. Rocky didn't travel out of state but at least has wins in season over Dana Hills (even if they weren't down a runner, Rocky still would have beat them no matter where he finished), Trabuco Hills, Seattle Prep, Star Valley, and multiple wins over Boise (Boise's #1/2 DNF'd at NXR NW, they would have been 5th with him finishing).