Like @Canucklehead, I think reactivations will be kept to next year. With no proper year three ETs new acivation. This would also allow new players that will arrive for Freelancer to unlock the suits.
As for December / January. All of the seven Hitman 3 ETs, and all of the six Hitman 2 ETs (sans the Undying) have already been used this year.
There are a bunch of Hitman 2016 that have not appeared in either the ETA, or as proper ETs. I would bank more on them.
As a reminder Travis did a poll of favourite ETs in march, and some have yet to be activated : the warlord, the pharmacist, the badboy, the sensation, … All were at the top of the poll.
I am personally convinced that the last ET of Year Two (and potentially of the game first activation) will be The Forger. He was the first in 2016, and I think it would be poetic to see him being the last.
Honestly, with all of the current unlocks and content, it feels like we are at the end of the base game life cycle. (emphasis on base game)
Link to Travis poll :