The guy said he will be coming back with more, and the most delay between updates was like 8-9 months -- something that happens all the time for commercial projects where you might or might not see an update in 1 or even 2 years.
In the last 2 months, he has been publishing an update dev release every 1 week or so.
August 2014 beta build was a really small update and the only one in year 2014. To be honest, my feeling also was that project has been abandoned. ST3 was silent for about a year and is supported by the single developer (as far as I understand it). No updates (except for one in August) in the times of Atom release, this looked like there was no more motivation for the Sublime Text developer. I am really happy that it's not true and Sublime is active again in 2015.
From the look of it, it seems that the dev works very intermittently on Sublime.
For my part, I would like to see something like LimeText (open source sublime clone) gain some traction. ST development cycle does not inspire me a lot of confidence.
I agree, that's why I say it was almost inactive for about a year, not 15 months. The point is, the real delay was bigger than 6-9 months, at least it's how the one could think about it.
For registered users it has been active again for the past two months—this is just the first stable release from that work. There was a noticeable silence from October through January, but lots of activity ever since. Hopefully it continues.
I tried Atom during the lull and it's gotten really great, but ultimately went back to the plugins/snippets I know and love.