At the very, very least it should be 12 months from today's date or the current expiration date of the deposit with the nearest expiration date from today, whichever is greater. Under the new rule this means that if I have two 2017 deposits that I want to combine that have expiration dates of Jan 2019 and July 2019, If I combine them in October I would then have an expiration date of October 2017.
If you have high deposits that don't need to be combined, you may have an advantage getting 12+ month inventory. It is also going to help those that search with points (RCI points, Hilton, Wyndham, etc) who will be able to start the searches early without actually tying up anything for 1-2 years.