Very interesting! Although I would rather have seen some of the table of contents concerning the Bestiary, this is quite intriguing as well!
I mean yeah technically Tieflings will have more subraces then elves, but I don't think they are culturally distinct from each other and I don't know if they are biologically distinct, we do know they are magically distinct. I don't think there are say Fiernian Tiefling civilizations vs Levitusian Tiefling civilizations vs. Disian Tiefling Civilizations vs Glaysian Tiefling civilizations etc...
I hope not!
Thats plenty, and elves better be less. But I am assuming that the monster stat blocks, including for Demons and Devils, are in another part of the book.
I am sad that they did not take this opportunity to expand on the modron vs slaad war.
Though honestly that would be interesting for a new setting, or a setting played at the age of Bael Turath vs Arkhosia from 4e.
Why do you say better be less?
I don't notice anything overtly there in reference to the 'loths. That's unfortunate.
Shemeska is supposed to be a commenter on the book. Like Volo and Elminster were in Volo's Guide.
There is also confirmation that more Yugoloths are in the book.