I was surprised to hear that Google are dropping support for ActiveSync connectivity used by iPhone’s (and other smart phones) to access Google free Gmail services which includes email, calendars and contacts from the 30th January 2013. It is important to note that support for ActiveSync will remain for paying GoogleApps customers.
What does this mean for iPhone users that have a free Gmail account?
It shouldn’t impact iPhone users too much but some reconfiguring of the iPhone’s Gmail account maybe needed. I expect that the iPhone email setup profile wizard for Google Mail (see pic below) will be updated so that it configures the iPhone to use imap.google.com instead of m.google.com, the latter being Google Sync (ActiveSync) connector.
I don’t think there will be any changes required for setting up Calendars or Contacts as it previously and for now will continue to use CalDAV and CardDAV services for its connectivity.
If Apple are slow to update the email setup profile wizard then you can setup your Gmail services manually by creating three accounts, one for email (IMAP Account), one for calendars (CalDAV), and one for contacts (CardDAV).
Below are some links to help you with a manual setup: