It's hard to say and every situation is individual. It will depend on your wife's overall condition and how she is assessed through the medical, including projected medical costs for the future. With a serious disease such as this, it is possible that IRCC could say she is medically inadmissible to Canada due to excessive burden. If that happens, you will recieve a PFL (procedural fairness letter) and will have an opportunity to try to address IRCC's concerns before they make a final decision in your application. Good luck and hope your wife's health improves quickly.