I get the logistical issues of two books, but it seems strange to release the players handbook without a release date for the GM guide. Do you need the GM guide to run a game? Or, at the least, if you want to start and build a long term campaign, is the GM guide required?
I imagine it will be like D&D where you can run the game with just the PHB if you had too.
Still I'm looking at my 5.2 Edition and wondering what they could leave out and push to a later book, and still have a playable game.
Technically you could leave out the chapter on family background, and still create characters that are playable, that could then be expanded in either the Gamemaster's Handbook or Noble's Handbook to cover more backgrounds than just Salisbury Family History, but I think you lose a lot of background doing that. They left it out the Starter Set with it's very simplified Character Creation and sample characters.
Clearly the chapters on Stats & Skills, Game Mechanics and Combat will be there.
I think a lot of the Ambition & Faith chapter could be moved to a GM's Handbook, or Noble's one, but some basic explanation would need to be there. Much of Wealth section probably could go into the GM's Handbook, basic play in Pendragon isn't really about buying stuff and you get much of you starting equipment just by being a knight, it's only later as you inherit and run an estate that details matter more so I guess that could move to the GM or Noble's Handbook.
In the Future Appendix which covers moving from Uther's period to Arthur's period could easily go in the GM's guide. The starter set seems to imply they are more focused on Arthur's reign and becoming a knight of the round table, than the period of Uther reign and chaos after it which 5.2 started in. So maybe Uther's earlier technology will be in the GM's Handbook and an updated Great Pendragon Campaign.
They can cut the scenarios, and perhaps have a simplified Winter Phase.
I'm also curious as to how they are going to handle a lot of the family stuff which is a major part of the setting, considering that female knights seem to be more than just an afterthought like they appeared in 5.2, how are they handling finding a suitable wife, random pregnancy (and deaths during) in the Winter Phase, all significant aspects of the earlier editions. A patriarchal society is a major theme of the setting, rescuing damsels, courting a wife at feasts, proving yourself to their father via quests, then leaving them at home to run your estate while you go off looking for the Grail, etc.