The overwhelming odds for a late autumn 767-400 flight are in favor of new seats. The seat map may show the old configuration now to avoid confusion in the event of an aircraft swap, but by the time your flight comes around, most ships should be converted. It's not a 100% probability, but it will be pretty close.

The 767-200 will obviously have the old seats.

As for the service, prior to 5/1 the flights had the CO-style "late night supper" which was slightly abbreviated, combining appetizer and salad courses on one tray. This was standard for CO BF departures after 10:00pm. There wasn't really much of a difference in the service besides that, but my recollection based on a handful of flights is that crews generally tried to get the service out/lights off a bit more expeditiously, and most pax opt to take their meals all at once.