e.g. humans don't have the long arcane mastery elves have, so far , but nothing is to stop this extending to a group or school that includes humans training to use the arcane in this way. however, because the elves arcane tradition is much more extensive including a lot of lost knowledge returning with the Moonguard, Highborne and Nightborne duskguard, the source of this expertise can come from there and only be limited to elves, Night elves have druidism to augment their mage arcane expertise in generating the elementals, while void elves have the void to make them more effective in addition to the arcane. However neither the void or druidism are entirely essential too, which is why blood elves can get it too.. druidism and the void just help make it better, something only the elves group have. Also having a priesthood also helps.. so you could say any race that has mage + any of priest, druid or void usage can effectively qualify and be reasonable to have a new group of people train to use the elements based on their arcane and druid/preist/void knoweldge.