I still hope the news is wrong with NBCSN about possibly closing.
CBSSN now airs Bellator MMA after formerly airing on Spike/Paramount Network. They are also getting the rights to a new auto racing series, and it's been moved to a more basic package on my local cable system, so I don't see them ceasing operations anytime soon, even if there's low ratings. CBSViacom has several low-budget and low rated channels that are somehow still hanging on.
FBN has been used for an overflow of Fox Sports programming in the past. Weekends are pretty much infomercials, even more than CNBC, so it should be no problem to carry sports on there too.