Don't get hyped up about the release clause, I call bullshit on that one
. Brandt extended his contract last year and Völler said that there was no such clause in his contract anymore. Nor do I think he'd be willing to move. Things are working out for him, he really looks f*cking incredible in Bosz' system. People in Leverkusen were extremely critical of him since he struggled under our (completely clueless) ex coach Herrlich whose misuse of Brandt alone should've been enough to kick him out. Now he's showing that there really is no German talent around he has to hide from. Honestly, he's that good. Those who've watched him 200+ minutes in his new role know that by now.
Since he's a really reflected person taking very planned deciaions I don't think he'll risk that one year before the next big international tournament. He can get much more out of a move in a year or so and if he continues this form (and I'm quite convinced he will), he can move under much more favourable conditions (financial and reputation wise).
He's best suited in one of the offensive CM positions in a midfield three I'd say. Perfect for a role like de Bruyne's or Silva's in City's squad or the Iniesta role at Barca. Since Bosz he also puts in the required defensive work and has consistently run between 12 and 13 km during 90 minutes. With him, Havertz and Aranguiz we managed games with 80% possession while still looking dangerous in attack. We even pinned Dortmund in their own playing third in the first 20 minutes and displayed a dominance you only know of Bayern or Dortmund under Tuchel.
Think I've never seen such a jump in such a short time from one of our players. I even struggle to think of any player that profited that much from a manager appointment. His development is truly great and in some months this will be more common knowledge.
However, if I had to guess where he's most likely to move this summer, I'd say Liverpool (Klopp's a fan of his and will have recognized his debelopment) or PSG (Rabiot leaving, Tuchel loves signing BL players and Brandt fits his system perfectly).