Oh please, first if the Dalish elves couldn't even hold to the land they were offered, what makes you think they'll be able to take any?
Second, city elves are a liabilty, not a strenght.
Third, the dwarves rely on the surface for everything that is not made of ore. They have enough enemies without angering humans as well.
Fourth, even if, miraculously, the elves won anything, all that would mean was that Orlais would move their borders East.
No it's the other way around. The Dwarves can and have done fine on their own, it's only a few surfer trader houses that benefit from the surface trade, a fact that is brought up in the assembly, "without the surface trade half our houses would go broke." and this isn't about all the surface this is about Ferelden, much of the Dwarves wealth comes from trade with the Chantry, something that is not being hurt by simply adding the Warden who gave them back their golems, saved their paragon, and put a king on their throne, underestimate just how much they would bend over backwards just for the sake of argument. We have seen they are willing to shut their doors to the surface entirely in one ending.
The City elves are a strength, it is only human oppression that keeps them weak, but had they something to fight for they'd show it, and even without weapons we've seen them still rise up when they got fed up with the injustices. So don't put them down, when they are being offered a chance away from human oppression, and a chance at real self governing. The Dalish have never turned away those who wish to return to the people. Not to mention how many Elves work closely to nobility, Anora herself keeps a handmaiden that is an Elf, as do many noblewomen, direct access to a potential ruler like Anora and Ferelden could again see yet another travesty befall it. City Elves would be the absolute first strike against the remaining human nobility, and after that total chaos.
This is all speculation though more fun than simply cursing world states and so on. They should work on that being a spin off IP in my opinion, Dragon Age: War, pick a faction, and crush whoever their primary enemy is. I'd play that until the end of time.