Сообщение от
Dave Froslie
Let me elaborate a bit on my answer.
The sealing will be on the application models and therefore it is an application release. The support policy that we're moving to is a 3 year model for application releases.
Per the plan that we published at Tech Conference and Cédric LUCHEZ pasted above, the last release that you can overlayer application code will be in the Fall 2017 release. The support policy provides you with three years of time on that release. But you won't be able to move to the Spring 2018 or later release. So Cedric is correct that your customer won't get new features from Microsoft or other ISV solutions.
Driving innovation into customer implementations as soon as possible is a driving force in this effort. You need to move to extensions for your customers to accomplish this