Welcome back Harbl, my younger brother has fairly severe autism(he does require full time care), and my parents often wonder the same thing you do - who's going to look after him when they're gone. Wish I had some answers to put you at ease but I do not. I've seen it my whole childhood, it's not easy to go through.
While you refocus on your family, I implore you to maintain some social/friend time, there's some support and relaxation. I saw it in my parents for decades, neglecting yourself too much doesn't help anyone, don't burn out. I've seen my parents go through a lot of what BSD is saying, except support on PEI is near non-existent, or was at least a decade ago. It seemed to amount to a publicly funded in school daycare for special needs. I hope I am wrong in remembering this, the people involved were at least excellent care givers.
You're definitely in the best province to provide the best for your children from the sounds of it.