Variety of options for UND and NDSU. What it likely will come down to is a mix of some of the following things (these are all theoretical possibilities):
I think 1-2 more sports can perhaps be cut
Continued faculty/staff buyouts
Reduction in graduate programs (Ph.D/Ed.D especially, but could be MA also)
Elimination of smaller undergraduate programs
Increase in teaching load for tenure track/tenured faculty
Continued loss of jobs (without replacement) in administrative offices (this really only has a marginal benefit in terms of costs though)
Reduction in research grant outlays
Continued closing down of older buildings, dorms, etc., as fewer students are on campus at UND (I think the same is true at NDSU to a slightly lesser degree)
Increase of tuition on Minnesota residents, but this would be marginal short-term benefit and potentially large long-term cost
Basically the same things that have already happened are likely to occur, but most likely with more elimination of programs. More drastic things are possible, but not that likely to occur IMO.
That likely gets an additional 10% cut assuming no larger structural or fiscal changes occur such as changing the Constitution to shut down 2-3 smaller universities or taking money from the Legacy Fund to offset a portion of this (I don't anticipate that happening; perhaps interest, but it doesn't solve the longer term fiscal issues). Depends really on what the Legislature decides to do as the ball will be in their court.
Unpopular, but theoretical larger things that could happen (probably not likely but theoretical possibilities):
Elimination/modification of/partial exemption to law only allowing tuition increases of 2.5% per annum I think(?), but that is really a long-term answer (although I think larger increases of MN resident tuition can be done, with potential loss of students from Minnesota)
Constitutional amendment with full court press from both state legislature and governor actively campaigning for change
Use of some money from Legacy Fund to reduce burden to some extent (not likely and would have relatively small impact I think, but would allow additional attrition from retirements and not replacing people who retire)
Differential cuts (different colleges/universities get cut different amounts percentage-wise rather than evenly distributed across universities/units within universities; perhaps the best, but politically toughest option)