I would not recommend anyone joining just for CET benefit at this time. Wait until February to see if CET will continue benefits.
There have been A LOT of changes in Diamond membership for 2018, so it would not surprise me if they do NOT continue this relationship.
That being said, I have heard nothing to suggest they are or aren't.
Luckily my membership is up in April so I can always wait & see.
I also recommend waiting, I'm a May renewal and gave them a credit card that expires in DEC 2017, just to make sure it doesn't get auto renewed. My guess is the partnership continues as the relationship costs CET nothing and the comps are based on play and not on card status. They lose a few bucks on resort fees, but I'm sure most people that check in are gambling and spending money at the casinos. Even 7 stars have been cut back on the free rooms they used to demand just for being 7 star. Charging for entry into Diamond lounges is another way they deter abuse of the system. If the partnership goes away, oh well, it was fun while it lasted.