VickyD
Seems Aldmer became Altmer, Chimer, Bosmer and Orsimer. Then Chimer became Dunmer.
[Please note that Dun and blue are totally different colours ... apparently either a graphic artist was colour blind or some dev did not actually do his/her homework before the game went to 'press' - these things happen - so I suggest you ignore the pretty blue colouring.] Mind you, like it or hate it, it made dam sure that none of th eDunmer totally forgot about Red Mountain and Azura's curse - which was precisely what she intended to achieve.
Admittedly Reiklings are a
lot smaller than Bosmer males ... but as a whole the above indicates a certain 'plasticity' in mer genes.
Not sure about the date of the Snow Prince book, but the Nords arrived in Skyrim a long time ago.
Lore-wise there could still be snow elves as a significant distinct race but this has yet to be either ruled out or established in-game. If you really want snow elves then mod them!
In a future release? If they went underground (3 dimensional habitation can provide enormous 2D living area) or moved to another Plane then they could make for a big surprise. Consider the Giant Goblins that arrived in Hammerfell from another Plane / Dimension / wherever and you have a precedent - especially given that those goblins were not known for either being smart or magically gifted ... food for thought. Who knows?
If you were entering into a writing competition then spelling should matter - but in TES writing competitions that does not seem to matter. What is really important is what people feel about what you have to say.
So you are neither wrong nor right on all counts.
Ofc - if you set up a forum and a Dev starts openly posting there and you put in a lot of hard work making it useful to people generally then you may find yourself in a position to create some Lore of your own and have it generally accepted. Until that time you're likely to find that any openly 'speculative Lore' you offer here may be given a rough ride - even if people like you.
all the best,
raggidman