AIR may not be dead, but I think that it's pretty safe to say that Flash Builder basically is. It's never getting an update again (unless it's a security update for something extremely major, and even then... maybe not). The workarounds to keep it running have been piling up pretty high. If you keep using Flash Builder, you should be doing it with the understanding that your next major operating system update is likely to break it completely because, sometimes, there simply won't be a viable workaround.