Why he should not play ? I guess he does.
It's written he is out of Monte-Carlo's alt list where he was number 4-5 or around. I doubt that's because he's got a WC or something so
But I would really love him to play in Houston! Which is unlikely though.
As for the Davis Cup, I don't even know. On one hand, it may discourage him, that he, who's participated in two DC finals, can't be selected to the team... moreover in such team where there are no clearly far better (except Richard) players than him. On the other hand (and I do hope he's going to follow this way), it may otherwise bring him some new motivation, a wish to prove it everyone around that he is still that Sebastien Grosjean who's been world's number 3. In general, I think it's good that he comes even if as a 5th player.