Well, the important thing to remember is that it isn’t accurate to say “Microsoft isn’t fazed by the reaction”, but rather “Microsoft claims they aren’t fazed by the reaction.” These are not the same thing at all
I would be very surprised if they were not seriously reconsidering their plans now. I don’t expect the XB1 to have this online requirement for single-player games more than six months after launch (if it even launches with it!) - I expect them to quietly turn off the whole system and patch the OS to remove the de-authorization and re-add a requirement that the disc be in the drive.