Some of them run grad programs that are pricey and paid for by employers, and that, combined with some endowments and good leadership, gives them a chance. e.g. St Ambrose churns out a lot of MBAs funded by local employers.
So does Mt Mercy. When I worked at Collins I swear half the employees were getting an MBA there on RC's dime. From my experience with the results, it was not a good investment...
In the end, there will be "consolidation", and it will be difficult how it's done. Take Coe & Mt Mercy. Coe has the athletics, a name a lot of cash due to Marv Levy and some NFL guys. Mt Mercy is just up the hill from there, and not as good in most ways, but has a ton of reach with their grad programs, and the Church of course. If they were businesses, the case for a merger would be obvious. But they aren't. IDK how they work it out, but together they would be 1+1=3 imho.
Places like William Penn are probably just toast.
One thing to keep in mind, if you are looking for a "villain". The huge push for community colleges (Kirkwood and DMACC esp) has dramatically increased their enrolment, and they are state subsidized/run and a TON cheaper than all the privates. Why pay $100k to Waldorf when you can go to Kirkwood for $10k, and likely transfer to UNI, Iowa or ISU anyway if you decide you need a BA? Now, I think what KWood and DMACC are doing is good, we need more people better educated, and to some extent they make up for the failings of our high schools. But the impact to the privates IS a negative externality of that good...