My guess is any such collapse (if it could even happen, sans some pretty serious privacy-protecting regulation) would be very temporary. Free ad- and spying-supported services make all sorts of other business models very difficult or untenable (see, for example, private, local voice recognition—why offer that product when you'll surely fail because the spytastic Google/Amazon/Apple/Microsoft offerings are free?) and even weaken the motivation for community-driven and Free, open source competition. Those other things would fill the void left by the death (please oh please) of the spy/ad economy. Hell, traditional non-spying ads might even make a comeback.