Excellent answer from Maria. All those are things to consider.
And I'd add one additional item: If they do default as tenants, are you prepared for them to go into court and argue that you'd actually agreed to sell the home back to them? You haven't, and unless they forge some documents, they won't be able to produce any proof. But that's an awfully powerful argument and you might find yourself in really big trouble.
It's your house, so you can if you want to. But whether it's in your best interest is another matter.