I doubt he'll do THAT well, like Mimi mentioned, he's not 24 years old anymore and is indeed a grinder so it would be pretty amazing / lucky if he really held up physically well enough to be a threat all season at the remaining slams.
I do hope he comes back strong though! he's obviously a fighter so at the very least we'll have to expect him to make it pretty deep in a few big events. a dream come true for sure for me would be if he came back and won the Roland Garros / Wimbledon duo, but I think the more realistic view point is that he wins neither
it is hard to say either way without having seen Nadal back on court, of course we all hope he is well so tennis will be much more interesting again