Absolutely the same position here like Romkabouter. I'd pay for the upgrade, too, but communication was too bad to pay in advance.
If we do not get any reliable roadmap I will probably switch to JCB (
link). Its a Joomla component that will generate the coded component. Its installable in the same installation and downloadable afterwards. This way you don't have to be frightened that one day this page will suddenly shut down, because the magic behind is installed on your own server. Looks like a good alternative to me. J4 is in active development, project is open source and does not rely on one person. There's a workaround that should lead to an installable J4 version on github. I'll definitely keep an eye on it.
Once again: I do not want to switch, like all of you, because this ends up in a lot of work. But it feels like we are not gonna get around it. That's why I asked for alternatives. If some of you find other ones, please post them here or send me a pm. Thanks!