The Blood Elves and tauren, druidism and the light
Now to be clear, I don't think Blizz will end up going this route because I don't really have much faith in their writing these days.
If Blizzard was to ever introduce druidism to Blood Elves, I think now is the best the stage has ever been set for it. In addition to the renewed cooperation between the elven races, I think that the lightbloom provides, in my opinion, a very compelling path towards druidism for the elves of Quel'thalas.
A major barrier to Thalassian druidism has always been a lack of a real strong hook that would interest the high elven populations. They have had a strong affinity for arcane magic, fel magic, and light magic, but the most interest that high elves seem to have taken in the natural world is through the Farstriders, which lean more toward the survivalist aspects of nature. Blood Elf respect for the natural world is a bit scarce - we have quests in which we curate the native animal populations; Quel'thalas, as we have seen it, is a fairly manicured society.
If we ever got Thalassian druids, I expected it to come from their proximity to the Amani trolls. They have demonstrated an affinity for Loa-based druidism and with easing tensions in recent story developments, we are seeing relations improving. On the other hand, It would be a tough sell to a lot of the elven population - it is something they've fought against for a thousand years and they have no particular interest in the Loa or any other local wild gods.
Recently I've been thinking that the Tauren of Thunder Bluff - with their worship of the light of An'she stemming out of a cultural movement amongst their druids - might serve as a bridge towards druidism through a reverence of the Light. In Tauren druidism, Light is as much a manifestation of the earthmother as the arcane power drawn from the moon. Lightbloom - which we know the Blood Elves are actively studying - provides the perfect opportunity to explore the space. Their worship of the Light puts them in a position to be receptive of this particular manifestation of nature, and they have allies who have specifically practiced and studied the intermingling of and relationship between the two forces.
One of the most interesting aspects of the lore, to me, has been the exploration of what the different disciplines look like in the cultural contexts of the races that practice them. Many people bemoan Sunwalkers and Seers (because they don't actually know the lore behind them), but I find them to be some of the most compelling combinations available. Its interesting to see how different populations approach interacting with the Elements or the Light and how those differences of depiction or practice amongst the different cultures.