No, flash is still supported by Adobe on linux. Only security updates, though. No new features. The last update was on 8 April.
I agree with that sentiment. Sometimes, however, there are circumstances in which you just can’t say no.
In case anyone else has this problem, the issue seems to be that firefox retains stale information about the plugin status. You can force a refresh as follows:
1. Exit firefox
2. Uninstall flash-plugin
3. Start firefox, and exit again
4. Install flash-plugin