I have a solution that might work. I feel it allows the continents to be for all intents and purposes belonging to races of each faction, but with enough grey spots that allow things like the Blood elves to keep Quel'thalas. How? like this
Develop a story that makes sense given your new changes, but one ultimately people would like, don't revert, move forward and find favourable things people are going to like. If people are angry and annoyed because of teldrassil and kalimdor, give the night elves something better - to make up for it - don't reward the humans instead, that's just warped. e.g. night elves settling in Darkshire or Gilneas IS NOT rewarding, it's a step down, however takingo ver thebroken isles, with a unique fate for northern kalimdor - well that might just work.
- Forsaken lose Lordaeron, give them something better, like Icecrown and Theramore.
- Make and give better things. I would give the night elves the Broken Isles, and relocate the highmountain to Stonetalon Mountain or they could stay there and just not really be involved in faction conflict, I would split the nightborne such that some ally with the night elves, while some leave and share with the blood elves, eventually I would re-unite them together regardless of who their friends are with Suramar still a home to the horde nightborne - the nightborne would have satellite place in Kalimdor, and actually work with some night elves there - e.g. Feralas being an area night elf, nightborne, Tauren all co-exist..
- I would also keep the blood elves in Quel'thalas, but with the high elves and void elves, of all the theories I saw, the best one was a forced truce, where the war went to Quel'thalas, with the high elves and void elves leading the effort, but it brought the Sunwell to near destruction, which is the one thing neither elves in the faction want. So instead they called a ceasefire and entered a truce where Quel'thalas would be horde/alliance represented only by the children of Quel'thalas - and any non-Thalassian in any faction would need permission from their Thalassian representatives to enter.
It's the only way to keep the horde having access to Quelt'halas, with the alliance alos there. Not the same for Azuremyst Isles - not sure what tod o there, give the blood elves Bloodmyst and the Draenei keep Azuremyst as well as moving into Hillsbrad/Dalaran crater where they build a new city.
While the factions have their own separate areas, there is some co-operation/cross over in Azure/Bloodmyst, in Quel'thlaas, in Feralas and in Suramar.
- I would continue the fighting in other spots - Darkshore is a warfront between the Forsaken and Night elves, but Ashenvale is taken over by the Cenarion Circle, as well as Felwood, Moonglade, Hyjal - where druids of all races maintain it - the only type of night elves living in Ashenvale are the druidic community ones who have always been there. Tauren and troll drudis also live there. It becames like a druidic capital. Arathi and Blackrock are also fighting hotspots where the remaining horde still fight to reclaim what the humans and dwarves want control of.
- Moonglade and Hyjal remain holy spots, but hyjal has both druids and shaman as well as dragons guarding. Wild gods moved to Val'sharah.
- War spot can also open up in Warfront, witht he Forsaken claiming Icecrown, the night elves and high elves should take Crystalsong and clashes can occur betweenthem, in a geography that has undead aligned Zul'drak, icecrown and north eastern dragon blight, with an alliance held stormpeaks, Crsytalsong and Grizzly hills. Borean Tundra also has clashses, elves can move back into their ruins, with the humans on the western side, then the orcs and Taunka on the eastern side.
Howling Fjord is Vrykul dominated, Forsaken and human bases have a hard time holding their own.