How much do you think he will go for when the time comes? We talking Dembélé transfer challenging?
I think that's impossible to predict as fees are influenced by so many factors and there are so many uncertainties.
Right now, it doesn't really look as if the stars align for a bidding war. Solely based on the reports I read there are only two serious interests:
Wirtz likes Barca and Barca is in contact with him since years but they lack the money to sign him this summer. The player's camp has already told them that they won't wait for them if another offer arrives this summer. Barca is also working on a Felix transfer. A formation with Wirtz, Felix, Gavi, Pedri and de Jong could be very difficult even for Xavi.
Besides Barca, Real seems to be seriously interested. I'm a bit skeptical as we don't even know their coach for next season, are also pursuing Mbappe. A formation with Mbappe, Vinicius, Wirtz and Bellingham in it isn't impossible but a challenge. They are also linked with Alonso whose formation actually fits all those players.
Then there's also Bayern who are said to be interested but not willing to break the bank for him as they are planning with Musiala and expect Wirtz to be too expensive. And that was before they signed Kane. Considering that they need at least one RB, one CB and one CDM - if possible even in the winter - I doubt they are serious contenders for his signature. If Musiala leaves that might change but I only believe hat when I see it plus even then it might not be enough.
City is seemingly interested but there aren't as many sources as for the previous clubs. However, I think City is generally the most likely destination as Wirtz admires Guardiola, City probably wants to prepare on KdB declining and Coty having the funds to sign Wirtz.
Those clubs aside, there haven't been any serious reports.
So if Wirtz moves this summer, it will probably be between City and Real - who might become favourites if they land Alonso and don't have to pay a fortune for Mbappe. That wouldn't be enough for a crazy fee like Dembele. That might change if we actually win a title. But I wouldn't rule out that no great offer comes in and he stays for another season. Then, a whole bunch of clubs could throw their hats into the ring and Barca might be in the pole position.