ESRI insist that there no plans to remove the WAB which is based on JS API 3.x.
However, this FAQ posted at:
https://developers.arcgis.com/javascript/latest/guide/faq/
It says clearly that currently that they just fix bugs until it retires on 8/1/22.
What is the status of ArcGIS API 3.x for JavaScript?
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
