Seems to be some morphological changes already?
https://www.bbc.co.uk/news/world-europe-53612856
When the urban foxes are seen wearing the flip-flops they steal, I'll worry....
Meantime, even in Britain, there are regional differences. Northern Scottish foxes average bigger and heavier than Sassenach ones. Mind you, I think that's just an average - close acquaintance with a number of local foxes has shown me how different they can be in size even within the same sex. One of the things that makes a generalist successful is rapid adaptability to new conditions - but not so far that they can't adapt back the other way....
Of course, in smallish animals like foxes where the generations turn over in 2-5 years, quite rapid change at local population level is perfectly possible.
Anecdotally, my foxes are minimally behaviour-modified. I think we can safely exclude habituation from change - almost anything can be habituated. And my foxes are habituated to me and Marion only, anyone else appears in the street and they evaporate. They remain wild animals.
Incidentally I disbelieve pretty much all the stories of urban fox attacks on people indoors - where there are teeth marks I'd be willing to bet foxes are being blamed in attempts to cover up dog attacks.
John