He has a chance. There will be nobody at Vina del Mar to beat him, and that's where he should be most vulnerable. Sao Paulo has stronger competition, but Rafa should be in better shape by then and that trend continues in Acapulco where he could meet Ferrer, but Rafa should be in great form by that week.
It's a great way to get back on tour for Nadal. Start out with challenger level opponents and build up your game while slowly facing tougher and tougher competition.