The new Gmail launches to general availability from July.
The third option would be the default setting as well. About two months after July, all users who aren't on the new Gmail will be pushed across automatically, but they'll be able to opt out for the next four weeks. "They'll have the option to opt out of the new Gmail for an additional four weeks".
New Gmail is now available in an "Early Adopter Program" (EAP) with an option to try it out before the GA.
Google notes that 12 weeks after the general availability of the new Gmail in July, all users will automatically be opted into the new experience.
Google hasn't yet announced when individual users will have to change their inboxes, but at a press conference in April the company said it's planning the same kind of gradual roll-out for everyone. The opt-out will also no longer be available to users who've moved to the new Gmail already.
Considering most people seem to like the new interface, Google has made a decision to move everyone to the latest version starting in July.
It's not uncommon for Google to hold back a major redesign or set of features for its G Suite catalog of products to give professional customers a bit of extra time to prepare for the changes, and Gmail is no exception.
Here is everything that's new in Gmail - plus when and how you can try it. However, the roadmap makes it apparent that Google doesn't want to waste time or split its user base.
Google's slick new Gmail app is coming to everyone by the end of the year.