I joined their discord to see what's going on with the project.
There I asked about the progress/validity of the roadmap, and told them about the sentiment in this thread / the web in general (project seems dead).
This is the (official) answer I got:
We stopped keeping up with BitcoinTalk thread, but the lack of communication there does not mean that the project is dead. The service is up and running, roadmap is still valid, however we have spent quite some time on the project's internals during the autumn and have various things pending for release. We are working on a rather big update to wrap up the year, that will be rolled out gradually, and should have more news next week.
Also shortly after me someone else asked about new exchanges for PING and this was the answer:
We don't comment on that. Any negotiations with any exchanges are private, unless both exchange management and coin team mutually agree to disclose the details, which doesn't happen very often. So at this point we cannot confirm or deny any possibilities of PING being listed on any exchange, until it actually happens, if it does. That might be not a satisfying answer, but that's how things are.
This at least convinced me to not sell right now, hope it helps you guys as well.