Well it took me a while to read through all the comments.
First of all, I understand their - Qt's - reasoning. It makes sense from a business side of things, and they are getting rather big. Developing that framework is not the easiest task and they need money (sounds too familiar). This sucks, but I imagine we can keep the impact for our user-base to a minimum.
From an installation point of view, basically you have two options:
a. Go with the official installer and register for an account, or
b. use brew/port on Mac and chocolatey/vcpkg on Windows.
b. does not require registration, as chocolatey/vpckg/brew/ports build themselves and they do not force the registration policy. They also tag releases, which means that we could tag to a specific release for each platform. After reading a lot of messages on the mailing list, it seems that the main difference for LTS releases will be that additional to security fixes, adaptions of changes (aka compiler changes for instance) will no longer be available in older versions. I assume we will have the option to build a version of Qt ourselves which we could than add to the installation bundle. That option can be used from -dev or always the latest tagged release version. For Windows/Mac users it will not make much difference, as most Qt-based OSS projects don't focus on using a system-wide Qt version anyway and are fine with using a package-distributable version. It might present us with headaches in regard of supporting Wireshark on older Mac/Windows versions though, and makes our job a little harder. It also introduces a wider range of possible bug-hunts.
On the - user wants to develop a dissector - route, yes I agree, this makes our lives harder. Just developing a small dissector quickly will not be as easy as it might seem today (it isn't today as easy as it should be also, but this is a different issue). On the other hand, a lot of users struggle with today's approach as well. For the rest we can map out the chocolatey/vpckg/brew/ports route. Or switch to Lua dissectors, where we might need to find a way to package and distribute them properly.
Finally, I would not call it a day yet. Qt has become a very strategic project for a lot of people. I could imagine, that the outcry over this decision will be as big as the one 2015 over the first attempt to close down the installer. I could imagine, that they will backpedal the ideas a little bit in the near future, although I will not betting on it. Let's hope they at least give the LTS route another thinking and come up with a different solution. For the reasons mentioned above, I could live without the binary releases, having no longer an easily accessible LTS branch does hurt though.
Overall, I hope the impact will be - if anything - as small as possible and affect us as the core's more than our users.
cheers
Roland
