This is a rare case scenario. but there is no age for education. We only live once and there is no harm in trying. There is nothing to lose here although I would highly recommend to review other methods of going to canada such as skilled worker or other pnp classes. She should at least get visitor visa and look around canada. A solid research niche that would benefit canada is really important. Maximum gap visa that i have seen in my neighborhood was 6 years.... In your case, 25 years gap is unheard of. I can't say much but if she can co-relate her education and represent her 25 work experience as some research job working on something really good, she can request to continue her research in canada as phd where infrastructure and technology can support her which is unavailable in your country. Also her health should be okay as medicals will be an important step as well. Lots of funding as usual, a really really good university, a supervisor for research are other things to be considered along with a highly positive motivating SOP. It would be an interesting case even for the VO.