Most undergraduate programs are around 120-150 credit hours total; most courses 3 credits each. If your wife were to attend part-time, it could take her almost 8 years to complete. Has she thought about taking online courses? Some of them offer 4 credit courses and she can complete the degree at her own pace.

It’s important to talk to the admissions and academics counselors at each institution. Many are willing to test incoming students on “practical knowledge” and award academic credit that way. With over 20 years experience, your wife would almost certainly qualify. I would definitely recommend looking into that. Good luck!