I'm wanting to update a 2d webapp built from the source of webappbuilder dev edition to use the latest version of webappbuilder, and at this link it gives JSAPI 3.33 as the latest version for 2D applications. For features such as the main basemap, I can find equivalent classes in 4.16 such as Map. How long will JSAPI <4 still be supported, and should I migrate my app to 4.16?
We are continuing to release version 3.x with bug fixes only (essentially maintenance mode). It is slated to be retired on August 1, 2022 however we will continue to host all versions on our CDN for the foreseeable future (so apps built with older versions of the API will continue to have access beyond the retirement date). See the Product Life Cycle document for more information.
Our premier web mapping API, version 4.x, now offers optimized performance and an extensive suite of capabilities far beyond what 3.x provides with a few exceptions. Developers should use version 4.x for all new web apps and evaluate whether it makes sense to migrate existing 3.x-based applications to 4.x based on app requirements and strategy.