Heritage quest says otherwise. They have preserved their culture and returned to their ways prior to the sunwell being destroyed. They certainly consider themselves high elves, their name is meant solely to represent the honoring of the dead. Not sure why this is even being stated given the nightborne quest and lorthemar stating "we value the ways of our people.".
Red herring that is entirely irrelevant given that blood elves also speak Thalassian. Seriously, what relevance does this have to anything?
Again, entirely irrelevant.
Blood elves are high elves. They have the culture, language, and everything else associated with them prior to the name change of WC3. Arguing otherwise is disingenuous. If anything, you should be saying that the high elves represent a change. Which is ironic that those who changed their name preserve the high elf ways, and those calling themselves high elves are leaving behind well...what was high elf in the first place.