I like to extrapolate. Let us extrapolate.
Currently, the events of the Siege of Orgrimmar place us in the year 31. Let's fast-forward two thousand years. What sort of Azeroth will we have in the year 2031?
To make this interesting, we will make the following assumptions:
1) Azeroth and its' people survive whatever is thrown at it. Sargeras and the Old Gods are, somewhere along the line, permanently defeated and/or locked away properly.
2) Long-lived races continue being long-lived, but will deal more and more with the short-lived races, like they have been for a few decennia already.
3) Goblin / Gnome engineering rivalry remains and flourishes with technological discoveries.
4) Magic remains in use and does not 'die out' because of Reasons.
5) It will not be "Warhammer 2K", that's a boring answer. Quiet you.
Compared to a magicless world like earth, 2000 years of only 1 dominant race has been quite a trip. What do YOU think would happen on Azeroth in the same timespan, given what sort of technological marvel they're already starting with?
Night Elves and the Cenarion Circle adopt the druidic teachings as a universal message of Life. Utilizing technological advances, they flourish as planetary terraformers, seeding otherwise lifeless worlds with boundless flora. Initially, they will use the Draenei/Naaru space-faring vessels for this, but eventually, they will develop their own mode of transport. Half engineered, half naturally grown. Think spacewhales, but botanical ones.
Gnomish and Goblin technological rivalries will lead to increasingly violent wars of espionage, sabotage and a weapon race of world-threatening proportions. Alliance and Horde (or whatever their paralells will be 2000 years in the future) will eventually form a NATO-like organisation to limit the advance and resulting violence.
After the defeat of the Burning Legion, warlocks completely vanish over time. Shamanism takes over throughout Orcish culture, and through practice, ancestral guidance and discoveries, many Orcs eventually shed their mortal forms to completely live as spirit creatures. This creates a new schism in Orcish culture, physical VS incoorporeal.
Forsaken make use of the dicoveries in alchemy, medicin and technology to bind their spirits to machinal forms. Removing the constant pain and agony they are burdened with, their outlook on 'life' (and what life means to them), changes enough for them to be less shunned by the rest of Azerothian society, eventually leading to complete reintergration with the rest of the living world. As awesome punk-haired cyborgs.