So in other words, they don’t take away as much as show another side that the Night Elves might not know or recognize.
More or less, the HMT do nothing but give Horde a non-elf race that fought in the War of the Ancients (some might say Nightborn count, but a) they are elves and b) they hid themselves away).
Thing is, history, and lore, are filled with more then just one race, if Night Elves kept their lore, HMT and Nightborn might not get any, yet if HMT and NB get any, some Nelf players might say they are stealing Nelf lore.
Hence my extreme sarcasm. The only thing that even drove a wedge between the HMT and the night elves was Sylvanas and her machinations. Before that they lived in neighboring territories for thousands of years.
Shadowlands lightforged rogues, hmt get rogues, priests and mages.
Blizz says vthey are working on working toward a place wherebrace isnt a limiting factor for classes. Which means they set up lore/time skips etc reasons to make it make more sense.
I think most races or all races on alliance can already be mages and priests.
Blizz has to setup lore for other classes lick warlocks, paladins, shamans, demonhunters.
New evokers would need more lore for other classes. Imo dragon magic would be nice to have for other classes. Elemental dragon forms like primals wouod be cool for other races imo.
Monks Currently I believe would be the next race to easily give everyone access to.
Lightforged warlocks would need explaining. But we have seen demons like Shivarra use both holy and fel magics. Dranei is more cultural for being at war with the burning legion.
Shamans I think wouod be cool if the elves and other races learned it as a form of battlemagi/ elemental specialists. We have seen elemental specialized mages and elven shaman in twilight cults.