Your right humans spread them as semi wild pets to protect they food stock from rodents but for Europe that where the romans over 2000 year ago, so i would not say that they are a new emerging existencial thread for the eco system here, if that was the case it would have long colapsed lol.
This isnt an extinction event caused by a slow climatic change or something, in some places on earth its an invasive species and if you look up how fast/slow they cause damage than its in the range of tens to hundreds, not thousands of years.