Autistic DM (he/him)
That would be awesome! If they did a First World campaign setting book that had the "Hobgoblin of the Feywild" (please be named "Boggart", please be named "Boggart"!) as the progenitor race to 5e's 3 goblinoid races (well, 4 if you count Verdan), I would buy the heck out of that book. I would also love to see if the did similar things for other races, like having Eladrin be the only Elf Subrace in the setting.I think the speculative First World setting is more likely to connect fey goblinoids* with miniature dragons. Then the versions presented in Volo are their degenerate decedents.
*The lack of goblin and bugbear lineages in the UA should have tipped us off that something was fishy about the inclusion of the hobgoblin.