I guess it depends what you mean! The old Gemini 767 is a decent mould but it is obsolescent too. Clearly a lot of the new moulds (737MAX, 777s, 787s etc) are much superior but I guess you could argue whether they are Gemini's moulds or JCs.
The new 767-400 wing won't be attachable to the 767-300 mould due to the different mounting.
I'd been aware the 767-400 has been coming for sometime but it is just one of many moulds JC are developing. However, since it is one GJ wants I suspect it'll arrive before the A310, An-24 and others!