I am very excited to get my hands on this Playtest. Weapon mastery was a (small) step in the right direction for martials last time, and I very much want to see it refined to allow for much more tactical play. Casters have a wide range of options they can use mid-battle. Martials should be able to do the same.
I kind of wish they'd just go for full 6e. I have a feeling that these new core books won't sell as well as they hope. Sure it might have a boost from the hard-core market immediately. But what incentive is there for the casual players to upgrade? They said themselves that the old core PHB will still be usable along side the new one. So really as long as the DM has the new book there is no reason for the existing players to upgrade.
I think they were totally going to and decided to back out last minute. It's gone from DnDnext to oneDND, and now it's called DnD 2024. At this point it's just a slight update