If that's the attitude, it's a somewhat dangerous tactic.
All developers should be ensuring their current version is stable, and releasing bug and security fixes as necessary. It's somewhat understandable not to be working on massive functionality updates, but to not maintain it at all will just tarnish your reputation and will frankly make people think twice about using your products in the future.
However, this is also the nature of the beast which, as far as I understand, is a common pattern throughout all platforms. You develop a product, you maintain it for a bit, real life happens and you disappear. This, in most cases, is the more logical explanation, and has been true for most of the more well known developers who have departed in recent years.
Also, anecdotally, when I last looked into it, 2015-2016 has so far been one of the busiest years in the Resource Manager with more updates and more new resources being posted than ever. It doesn't seem to me like that's on a decline.
Thankfully we have some very interesting and exciting times ahead in terms of XF development with XF 2.0 getting closer by the day. We're still on target for having a publicly accessible demonstration installation and the sooner we gather the feedback on that, the sooner we can get XF 2.0 in the hands of developers (and anyone else who is interested in playing with it) which, I have to say, is a generally far more enjoyable experience for developing than XF 1.x... and that's coming from someone who loved developing for XF 1.x.