General Anakin Skylwalker targets Obi-Wan Kenobi, out of hiding with his attack action.
Obi-Wan uses "Mind Trick" but doesn't have any other available target so the combat action ends.
Can he use "I'm going to end this" on Obi-Wan Kenobi, out of hiding?
My interpretation is that he can since Obi-Wan is still the initial target of the combat action. Nothing on Obi-Wan's card says he is removed as a target or cancels the whole action.