I think adding football or lacrosse is becoming a fool's errand for many schools. Football is an extremely expensive start-up and, as others have mentioned, has a questionable future (and is obviously expensive to maintain at any level, much less at a successful level). Lacrosse, while potentially more viable in the long-term, has - I would argue - gotten ahead of itself at the Division III level in non-traditional areas. There are a number of Division III schools in non-traditional lacrosse areas that have struggled with numbers (some that have even already shuttered fledgling programs) because the number of high school student-athletes in those areas simply hasn't kept pace (though it's growing on that level too) and many of those schools (especially in colder-weather areas) have a tough go of getting kids from areas where the sport is much more widespread. I think some of these midwestern schools, around 5-10 years ago, saw lacrosse as a panacea that would bring them 40+ men (and at least 20+ women) and that simply hasn't happened in a lot of cases (with some very successful exceptions). I think we will see a cooling down of lacrosse expansion (it may continue to increase, but at a much slower rate) at the Division III level while high schools in those regions play catch up.
Too many institutions are trying to lean on adding high-roster sports to boost male enrollment or overall enrollment. There's a bubble there. To be successful in gaining traction in recruiting battles, there are very real capital and operational expenses that the institution needs to be committed to. On top of that, with recruiting battles at the admissions level already very, very real for many Division III schools (especially non-top tier privates), more schools adding more sports is creating a greater demand without necessarily increasing supply*. In short, I see a Division III athletics bubble in our future within the higher education bubble in general. Assuming anything else would seem unwise.
*That supply being high school student-athletes who are interested in/can afford an education at a small private school.