For what it's worth, kicker are reporting that Klaus Allofs, Wolfsburg' director of football, said that top clubs have turned his head with insane wages. They also report that De Bruyne is interested to move, but would prefer to stay in the Bundesliga. There aren't any quotes backing that up though.
What's really odd, there still aren't any rumours in Germany that the deal with City is close to done or anything like that. I know that's what's reported in England and Belgium, so it could be true of course. Still find it weird, that no German newspaper jumps on the bandwagon.
My personal opinion (and it's really just that, basically a wild guess, that could be totally wrong and isn't based on any facts):
Wolfsburg will turn down City's offer, De Bruyne will stay one more year and get a crazy raise for that year without a contract extension, then he'll sign for Bayern next season. It'll be handled very early, so that Wolfsburg have all summer to find a replacement and invest the money in a smart way instead of now looking for a last minute panic buy.
But then, maybe City just ups the offer to a number that neither de Bruyne nor Wolfsburg can refuse.