We are all for this: "to canonize exemplary non-Catholics such as Mahatma Gandhi or Nelson Mandela!"  A Vatican II Church in union with Rome would have done that years ago.  https://RiteBeyondRome.com  

As for our Roman Rite/Church, when will we start considering it in its self-named "elder brother" status in our Catholic family of 22 Rites/Churches already in union with Rome?   Siblings don't have to agree with each other in order to be sister or brother to each other.  That doesn't mean we have to dismiss them for their beliefs either.  We could all be a challenge and a gift to each other, no?  ...with the appropriate space between us for our differences.