Active domains created before June 22nd will continue to enjoy a 90-day rolling grace period for loads in excess of the free, 25,000 loads per day until October 12, 2016. After October 12th, developers must have billing enabled to avoid an error after the 25,000 limit is exceeded. Those already paying for overages will experience no change.
The nuances of the Standard Plan updates are a bit confusing, and those who might be impacted are wise to review the updates themselves. Google has provided some FAQs addressing grandfathering, changes to the Places API, billing and billing enablement, loads in excess of the maximum limit, domain changes, keyless entry for grandfathered-in accounts, nonprofit use, and media use. Apps created on June 22nd and after are subject to all the new updates.