Microsoft has a notorious penchant for disrespecting user preferences in favour of market share. They were known for steamrolling IE as the default after every patch of windows, so im anticipating the "bing" default to get applied every time a windows patch is rolled out as well.

Users will probably (rightly) see this behavior as an error and go back to using Chrome. Heck, it was part of a litany of chicanery that spurred the exodus from IE.