He's a good player, Magicpole will defo testify to that. 1 that I think can succeed with the right move down south.
However, if I was an interested club, I'd maybe hang fire for a month or 2. Go in early & Celtic will probably demand £30M+. However, they have Champions League qualifiers in August & September. If they get knocked out them, they might be more open to negotiate to balance the books. He also has 2 years left on his contract, much will depend if he extends on not over the next couple of months.