If Nadal is not able to defend his points in all 5 Masters coming up, it may last more than you think. Ferrer will surely play 250s and 500s. The points he drops from any 250 have no impact on his ranking points. If he drops a win from a 500 tournament, he only loses a maximum of 250 points. There is no way Nadal can catch up to Ferrer unless he scores: SF in IW and Miami, win in Rome and Monte Carlo and QF in Madrid, and even so, Ferrer must do pretty badly in those tournaments. Also, Nadal needs to defend his RG. It's more likely that Nadal will drop further, rather than catch up with Ferrer.
Sounds good to me. I'm thinking that it will take Nadal a long time to get back into the same form he used to be so I suppose you are right.