I'm not really familiar with these races, but I've heard about The Tsaesci Race. I'm guessing they still exist somewhere in Tamriel, and not all of them has gone extinct or anything like that. Probably wiped out by the thalmor, if able or anything like that, i don't know :p
I'd love to see the new TES game being around this parts of the lore and trying to integrate them in the current state of tamriel when the dragonborn is around and probably trumpets blaring to hail him/her.
When ever I hear about these four races, I just think of armies of Snake People going to war against armies of sabrecats. They all just sound like quadrupedal beasts fighting each other when they actually have lots of culture and Major cities. I just can't really see myself fighting a talking sabrecat.
In the more abstract sections of Apocrypha's library, lore nerds discuss time and directions as being linked. Tamriel is the center point, and the present. If you travel North, time stands still (this is why Atmora is "frozen" in time, not temperature), if you travel South, time becomes erratic and unstable (Altmora/Old Elhnofey as the lost homeland of the Elves is often thought to be in the South, and so it doesn't exist anymore because of the effects of time, leaving it but a genetic memory in all Elves). The Nords since old times (and all men to a lesser extent) are described as constantly changing their minds so their thoughts don't freeze (because Atmora became locked in time, they fled this stagnancy in thought and action). Almost all elves want stability and are epitomes of stasis. They physically age slowly, and their cultures are about preservation of the old. They fear the chaos of untime.
So, North times stops and South time breaks. Center is the present and normal flowing time. West is supposed to be the past (specifically, the previous kalpa or reiteration of the world) while the East is the future.
According to Kirkbride.