I've read that Ultimate Traffic and EditVoicePack are in the works to be released for FSX. Does anybody know if FSHotseatFX, AFCAD, or TTools (or anything like them by another or new developer) is in the works?

There are Afcad replacements in the works (1 even in beta). There are programs that convert back and forth between TT and TDBB style flightplans so you can keep using TT. I do not know about HotSeat as I never used it. For discussions on some of the tools being developed, head over to http://www.fsdeveloper.com/forum/index.php and check out the Scenery Design section. Especially check out the Afcad forum and SDE (Scenery Design Engine) forums.