It was originally estimated that encrypted searches from logged-in users would only conceal a single digit percentage of search queries--some placing it at 2% to 3%. In reality, many companies are seeing around ten percent of keyword search data blocked from their metrics. Search Engine Land has reported around 7% to 14% of keywords being blocked.
Search Engine Land has also reported that this new feature within Google is causing strong reactions in the website analytics community. Ultimately, organic search is becoming less trackable as a result. Advertisers on the other hand, still seem to be receiving this data.