As DYKWIA says, almost certainly will be the older version, probably only about 5% of the fleet (if that) have the new J config, and they seem to be flying mostly to the US at the moment from what I've read on here.

With regards to your tier miles, for your flights in December, all tier miles earned from last December (2016) up to and including your flight this December would be considered by EK for you to potentially gain or regain status, so not all is lost.