Drupal 9 is end-of-life and no longer supported.
Drupal 10 is the current stable version, and the development branch for Drupal 11 has just been started.
But what will be in Drupal 11?
Well, we don't know yet.
Drupal's release schedule is based on fixed dates and not on features.
Whatever is ready on the release date will be included. If something isn't ready, it'll be in a future version.
If something is ready sooner, it'll be in a minor 10 version, such as Drupal 10.2 or 10.3. We've seen it recently with various UI improvements in 10.1 - with more in 10.2.
We saw new features, such as Layout Builder, added to Drupal core within the Drupal 8 lifecycle, and there's still time to add more to Drupal 10.
Here's the thing
But, like Drupal 9 and 10, Drupal 11 won't mean a major rewrite to your code.
Drupal 11 is based on Drupal 10, so the modules and themes you use will be able to work with both, allowing you to upgrade incrementally.
While there isn't a definitive list of new features or changes for Drupal 11, based on things I saw and learned about at DrupalCon, I'm excited to see what makes it.
P.S. Are you still using Drupal 7 and don’t know what’s involved to upgrade to Drupal 10? Book a Drupal 7 upgrade consultation call or an upgrade roadmap.