When I say 'wish you a great summer' in an email to my friend, does it mean I will not write to him until the summer ends? Anyway that is what my friend thought although I didn't mean that. Have I misused the word 'Wish'? I doubt.
It ("I wish you a great summer") could mean that you don't expect to see that person again until the fall. Context, as always, is important. If you said it to somebody in an email that would be different than if you said it in person.