We could probably think of alternatives for most of these things, but there are a lot of people who just use what came with their phone/browser.

Additionally, think of all of the Google-backed services out there provided by other companies. How many companies use gmail heavily that would lose all kinds of records?

Normal people would lose their e-mail too, and businessmen would lose a lot of their calendars. The actual solution doesn't matter as much as the data already invested in Google's solutions that would be lost if Google just vanished.