Short answer: Yes, this is planned.
Be aware, that Elementor, and the Block Editor (aka Gutenberg) are the de-facto built-in Add-Ons/ Extensions for these builders. Once Elementor is installed and activated, you can use this integration. Additionally, once you are in a WordPress install that is in version 5.0 or higher and has not disabled Gutenberg you can leverage this integration as well.
Now, on to the longer answer to the original question: The support for other Page Builder plugins will be done as Add-Ons. Read on:
These Add-Ons have already been released:
- Oxygen Builder (first released in April 2019)
So far, I am planning the following Add-Ons:
- Beaver Builder (in development)
- Brizy (in development)
- Thrive Architect (in development)
- Divi (planned)
Please note, it is not possible to give any roadmap or release date. The Add-Ons will be released when they are ready, step by step.