I thought firebug was discontinued anyway... so I wouldn't hold my breath. But which features specifically are you missing in the browser dev tools themselves? Personally I'm mostly using chromium for development as I find the firefox dev tools a bit sluggish at times (especially the debugger), but generally both firefox and chrome/chromium provide really powerful tools by default.
PS: You might also check out the firefox developer edition, but AFAICT that's basically firefox with a dark default theme.
^^ You might get some more cutting edge features though before they make it to the regular release.