Uhmmm.... really can't say yet if I am interested or not.
About the lore part, probably I don't need. I'd like to play 5e adventures set in the Forgotten Realms, but since I totally disliked the changes during 4e, and the 5e realms still depend on those, I might just keep using my 3e FR books for the setting.
I would certainly be interested in the 'crunch', but I have to say that the page count doesn't look that good. It's hard to say from the ToC, but we have 24 pages for classes (2 per class), 12 pages for background (12 new backgrounds), and some races material as well.
Personally I think we need more subclasses rather than backgrounds. Furthermore, a background is mostly just 2 skills + 2 tools/languages + 1 downtime feature. The traits/ideals/bonds/flaws are very useful, tho not strictly 'crunch'. But besides new dowtime features, the rest is something that already exists in the game. You can just pick 2 skills + 2 tools/langs and have a new background.
OTOH new subclasses are not something that can be designed as easily as a new background, so new subclasses are really the main thing I would be looking for in a supplement book. It looks like every class might get at least a new subclass (except the Ranger, apparently) OR at least new sub-subclasses (e.g. new Totem animals), if this is the case then GREAT! At least we already know that some are certainly in (e.g. Swashbuckler). But it's not really possible to tell from the ToC, it might be that those 1-2 pages are just spent on rambling about "how to fit the existing (sub)classes in FR", which would be a huge disappointment for me.
I welcome the new races options however, especially Half-Elf and Tiefling 'option'. These would probably be a bit like subraces, and could have been in the PHB if they had designed them already at that time, but it's good that nearly all races get the same treatment (Half-Orcs being leftover for now).