Let's run the numbers:
All the subclasses to date fill around 35 pages. Downtime is 14 pages, feats are 5, traps are 13, and spells are 5. Battlesystem is 5 pages and encounter building is 4. Revised ranger is 8.
That's less than 100 pages, and we know that not all the subclasses are making it in.
There's a lot of pages of content we know nothing about...
Xanathar is the head of the Waterdeep Thieves guild, right? If Volo's Guide to Monsters allegedly presented that character's knowledge on the subject stated, then wouldn't it make sense to get Xanathar's commentary on things he knows about? That would mean illicit operations, factions and geopolitics in Waterdeep and the surrounding areas, goody-two-shoes who like to try to stop him and/ or the underlings who work for him (the player character options). As a beholder, he might have additional knowledge about the planes or the Far Realm that he might share, too.
"More details from Crawford My italics. "Xanathar's Guide to Everything has over 25 new subclasses; a host of new spells; new rules on magic items, downtime, traps; and more. #DnD"
So there are also new rules for magic items, new spells as well, a host of them even.
If it's anything like Volo's Guide to Monsters, it's Xanather's name on the tin, but he'll be relagated to mostly just the odd posted note in the background, so I doubt he will have much if any impact on the actual content of the book, he's just involved to attract realms fans.
Let's run the numbers:
All the subclasses to date fill around 35 pages. Downtime is 14 pages, feats are 5, traps are 13, and spells are 5. Battlesystem is 5 pages and encounter building is 4. Revised ranger is 8.
That's less than 100 pages, and we know that not all the subclasses are making it in.
There's a lot of pages of content we know nothing about...
Was anything said about what the page country will be.
I asume it will be a multiple of 32 like they normale are
No new surprises then? Bummer. I'll have to keep waiting for my Paladin of Freedom/Liberty.