Qt5.15 already unsupported upstream (except commercial license)?

I’m not sure if I understand correctly. But official support for Qt 5.15 (the last and current version of Qt5) seems to be discontinued for non-paying users:
[Development] Commercial-only LTS phase starts: Closing the 5.15 branch(es) on 5th January (qt-project.org)

Does that mean that we have to port to Qt6 already if we want to see future bug fixes from upstream?
Can we continue to use Qt? Or do we have to search for alternatives?

It seems to me that moving away from Qt would be a huge effort, so I hope we can continue to use it. It’s not like Qt 5 is going away. But I do understand that there could be maintenance issues if there are critical bugs that need to be fixed.

Looking at what is needed to port to Qt 6 would probably be a good thing to do, but I don’t know how easy it will be to move to Qt 6 now. I don’t see Debian packages. Is it packaged for any other major linux distributions?

It is in Fedora 34 (alpha stage at this moment, should become beta on March 16).
It looks to me that qt5 will be the default and 6 is available for dev.


The minimum requirements seem to be significantly higher for Qt6:
Supported Platforms | Qt 6.0
For Windows, that means only Windows 10 and only 64bit is supported.

Additionally, they seem to require at least C++17 (on all platforms):
Qt 6.0 Released

Since Octave aims to compile with C++11 compatible compilers, this probably means that we have to stick with Qt5 (at least for now).