Open sourcing some code means making it available under a license. That's it. No further promises are made by you. So you're free to add a notice that you won'

Open sourcing some code means making it available under a license. That's it. No further promises are made by you. So you're free to add a notice that you won't maintain it and that people are free to fork it and maintain it under another name. Or you could maintain it if you think it's good for your career and/or you simply enjoy doing it.