According to Umberto, once they finish CYVR (which should be soon if KLAX reflects the development timeline) they will begin work on the major JFK update. The JFK update, unlike the other updates for Zurich and O'Hare, will be a completely new airport in terms of modeling and texturing. This is what makes me so excited about it as a huge JFK fan. They are going to be redoing it and using techniques from KDFW, KLAX and CYVR -- and it will look as good if not better than those. It will also includes all the updates to JFK that have happened since 2008 and since it will most likely be released next year, they will probably (and hopefully) include the new additions to T4 since that will be opened in May. He said they are going to charge for it but likely give a discount to current owners of JFK (I for one am more than happy to pay for it)
If CYVR comes out in 2 weeks, let's say, JFK should probably be here by Spring or Summer. It may take shorter since they have already done it but maybe not because they are recreating everything... but I'm no developer so I'm really just guessing in terms of the timeline.
Hope that helps.