New Sites is now live and you can start to move all of your information from your Classic Site to a New Site. At this time, New Sites has less features than Classic Sites but new features will be added in the near future. See the comparison table in the link below:
The following has been taken from Google Site Help:
”We encourage organizations to start creating sites using the New Sites, which will add even more features and options in the near future. In the meantime, you can continue using Classic Sites to create, edit, and view sites.
Migration options to transition your classic sites will be released in 2017. Both classic and new Sites will continue to be supported during this time. Timelines and instructions regarding the gradual depreciation of classic Sites will be released in 2018. The specific deprecation date will be announced at least one year in advance.
You can migrate an existing classic site using the following steps:
– Create a replacement site using new Sites.
– Copy and paste content from classic Sites to new Sites.
– Add a banner to your classic site redirecting people to the new site URL.”