Which modern software is a decent successor / replacement for Fireworks?
Just to give a little context, I have a background as a design-savvy developer (not a developer-savvy designer). I worked at an agency many years ago. I've been out of the design game for about 3 years and starting to get back in. Back then my tool of choice was Fireworks, but I just learned yesterday that Adobe is letting it slowly die.
So what are the mainstream next-generation tools for someone who's doing exclusively web graphics and interaction?
Or, since that question may be considered somewhat subjective or "what's your favorite tool", is there an authoritative source that can give a good view of the web graphics tooling landscape?
Good question, for I too have been a lifetime fan of Fireworks (their entire lifetime). Have you heard of Sketch? I can tell you that it's the only thing that comes close. (It's a perfect mashup of Illustrator and Fireworks, but SO MUCH closer to FW). Your transition should be seamless, and you will quickly be in love. Personally, I'll still use FW until it's technically impossible.
Give it a try: http://bohemiancoding.com/sketch/
Also search for Sketch; you'll find lots of amazing plugins and third-party support sites.