They're updating the Vanilla and Dark Angel codexes in a week or two, so there's a full expectation that Heavy Chainswords/Eviscerators will be added options in the new 'dexes.
And, I'm not sure which one it will have, since Heavy Chainswords and Eviscerators have different stat-lines, yet the GW web page has it listed as either/or.
As for if it's worth it... well, it always comes down to what you face. Against MEQs, Str6 > +1 Attack, generally netting you a marginal increase in MEQ wounds. Against GEQs, it comes down to a wash, where you'll get more GEQ wounds with a normal Chainsword, but the Heavy Chainsword is insta-gibbing multi-wound models (and Eldar Exarchs, I should mention). So, thinking aloud on this one, I'd say that if the Heavy Chainsword was 5 points or so, it would probably be "worth it's points". Possibly 10, but I think that'd be a little too much.
The "chainfist" (Eviscerator) is another situational tool. Unfortunately, much like the powerfist of old, it can be challenged out easily. Yet, it does function well as a Melta Bomb+ for those that use their assault squads to go vehicle hunting.
At the end of the day, though, unless they do a major over-haul to the Assault Marine (doubtful), or they receive drastic formation bonsuses (possible), we still won't be seeing them on the table much besides MSU flamer drop pods, as they are often out-performed by our many other assault options (bike command squads, for example).