They really don't. The use of the ambiguous word 'evolve' has stirred the pro high elf community again. You've been stung since the big rejection in 2018 and have been desperate to see if you can find any way of either proving Ion wrong or arguing he, and by extension the team, have changed their minds so you can say 'high elves are back on the table's.
They aren't. The term evolve can be used, inappropriately, to describe a physical change in an individual. The pro high elf community has therefore latched onto this incorrect use of the term to argue high elves and blood elves are truly different things.
Yet the eye colour difference was one of several smaller differences cited in the big rejection between the two groups in 2018. These differences were not cited to acknowledge they are different, they were cited to make the cumulative point that these differences don't matter. Blood elves and exiles are biologically the same race who share a theme and an aesthetic. One of the demonstrated facts about their biology is that their eye colour is mutable under the effects of a dominant magical ambience.
In the past this was blue, reflecting their arcane sunwell . When it was destroyed, the dominant ambience became anything in the vicinity. This, for the blood elves, was the felt crystal brought back by rommsth from Outlander. The tiny coterie of exiles who remained away from quel'thalas didn't have an opposing ambience that could have shifted their eye colour. The opposite in fact as many gravitated to dalaran where arcane magic is used commonly.
Now however the sunwell is restored. A font of dominant light energy that both blood elves and exiles partake of. Eventually, as demonstrated by precedent, all who feed on the well will gain golden eyes.
The exiles and the blood elves share the same destiny as the same people with the same energy source. The void elves do not due to their void based nature. Cold blue eyes will doubtless be one of their customizations when their pass comes. It will help differentiate them from the blood elves.