I'm guessing they are keeping Timelord and not trading for Holiday if he was healthy and more durable, which he wasn't. Also, they must be high on some of their new guys (Walsh, Brissett; Still have Kornet, Hauser + PP) so they aren't too worried about the bench.
I still expect CBS to add a big man before the season, OR he might be fine just rolling with what they have and instead just using the future picks (all those 2nd rounders) at the deadline to acquire a big man (or through the buyout market). I mean lets be real, for this team all that really matters and what we care about is playoffs. They can survive the regular season even with the likes of Hauser, Kornet, etc.
If CBS is able to extend BOTH White + Holiday in addition to having Tatum, Brown and Porzingis locked up, then WOW. That'd be a helluva job by CBS. White and Holiday (especially Holiday) kinda strike me as guys who would be willing to take a little less to stay, just like Horford and KP. White/Holiday have made a lot to this point as well. Not like this is their first contract extension coming up in their careers