I mean Dante was probably not going to be around much longer(Hoenhime stated her body was rotting faster and faster) and since Greed is immortal wouldn't it have made sense to wait her out and hide some place far away while helping the brothers from a distance?

That's assuming Greed knew. Even Dante didn't know about her terminal inevitability until Hohenheim told her (and she denied it), and that happened AFTER Greed's death.