There are no plans for dropping ee8 support.
The only plans we have internally is related to how we build / maintain the ee8 support.
Eg: one proposal is that we take the ee# levels out of mainline into a new repository with branches for each ee#, making the mainline code tree just reference those via git submodules. This would help us maintain code changes across the ee# branches with simple git merge tooling. (This is just a proposal at this point in time, and we are focused on getting 12.1.0 out the door before we make any kind of change like this).
But, that being said, you should know that sticking with `javax.servlet` is already going to be difficult when it comes to interop with modern browsers.
New features being introduced in the browsers are not compatible with the old ee8 servlet api, and any kind of support for those modern browsers will mean proprietary apis or hacks to get them to work in ee8.
The fact that most libraries that support javax.servlet have stopped updates (including security updates) or reached end-of-life for those versions is another nail in the coffin for javax.servlet.
If you plan on supporting things on the public internet, or modern web browsers, then it would be in your best interest to migrate your webapp to jakarta.servlet when you can.
Yes, we know it's more difficult than upgrading from Java 8 to Java 9, but it's not something you can avoid in the long term.
If you have a totally in-house webapp, not exposed to the internet, and no modern web browser will connect to it, then stay with ee8 if you want. The only pressure you have to update to jakarta.servlet is lack of support and security updates from your third party dependencies that use javax.servlet.
- Joakim