A backup plan is a really good idea, and it'd be good to get this setup before you jump head-first into a career, simply because the last thing you want to do after a long day of work is come home and hit the books.
You could always fly for a few years and then look into doing a masters in aviation management or business management. I'm doing this at the moment and the workload is not too bad, not sure how difficult it would be to get in without a degree though.
Get a trade or study business, both of those would sounds choices in case your medical fell through.
toronto_flyer