They could explore joining the WIAC if they want to remain in DIII.
Being a DIII independent in many sports is hard because it is tough to create a schedule.
They could move to DII, which requires they find a conference and it takes a three year transition period (actually the article missed the fact that it could take another year if the fail any of the stages in the transition program, which is not uncommon).
Moving to DI requires being a full time member of DII for 5 years, plus a 4 year transition period and an invitation to join a conference.
Mostly it just quoted the NCAA transition rules.