In most regions where users would bounce off a different default and manually override it to Google (thus denying us an ethical defaulting opportunity), yes. Mozilla found out the hard way in 2014 December when they reset default from Google to Yahoo! in the USA, and most Firefox users Whisky Tango Foxtrotted back to manual Google setting. (Verizon and Mozilla bailed on that deal and Mozilla is back with Google.)
The good news is that we are partnered with DuckDuckGo already on private tabs, and as a promoted alternative engine -- and now we are switching default search in key European countries to DDG. We feel DDG's quality has risen enough, and certain countries are privacy-focused enough, that we won't lose too many users via default search override setting back to Google.
