Leaving Dortmund for those three would be a pretty weird career choice, though he'd probably make more money.
He's a candidate for leaving Dortmund, because he has relatively little chances of being a starter. He's not technically good enough to be more than a role player at a top club. I wouldn't be surprised if there was some truth to rumors linking him to small clubs: before he joined Dortmund it was reported that playing in England was a dream of his and that he was also considering an offer from Brighton or some other club like that. If he wants to be an important starter he can't aim very high, even though he's really good at what he does well.