Iowa's fourth season is the answer. No one in Nebraska wants to change their sport from fall to spring (or 'winter outdoor' season, as I call it). Soccer would rather move to fall. Softball won't be interested in the opposite change.
It has always been said that Legion resistance in Nebraska stopped the fourth season. I think that is waning as more and more Legions are having trouble getting numbers and coaches. I think they might be open to the Iowa system where they basically scoop up the high school kids for Legion tournament season.
The resistance that is not waning is the schools' not wanting the problem of a fourth season for ADs to organize and having to find teachers willing to take extra-duty assignments that go into summer months.
I imagine if any movement started, you might hear from football and basketball coaches who don't want to fight an in-season HS sport during their prime off-season months of June and July.
The 3-seasons were created for a 3-sport system: FB, BB and track for boys only. Now that we have a 20-sport system there are always going to be crowded seasons. There is no escaping it.
BTW as a softball parent, I'd love to be going to her games playing for a free HS team from May to July instead of the current system. Just know it isn't happening.