I suspect they wouldn't be that much different from the WoL. Even Sundered, the WoL's reserves of aether are absolutely ridiculous. Whether this means Azem was obscenely powerful even by Ancient standards or it's just the WoL's mountain of plot armor striking again is anyone's guess. Individuals with pure, Ancient souls and the amount of aether that comes therewith will likely simply be able to freely change between jobs as "we" do, whereas normal people are limited to 1-2 jobs at the very most due to how hard it taxes their aether reserves. I imagine an individual born with an Ancient's aether levels might also be able to freely employ extremely taxing magic without fear of depletion.
If, on the other hand, the introduction of the Ancients' souls into the system begins the process of restoring the greater whole of mankind to the state they were originally in, we might eventually (but probably not within the WoL's mortal lifetime) see such things as creation magick again. Interbreeding between the normal population and their excessively powerful counterparts is bound to eventually raise overall levels to something a bit closer to where they were, although very likely not all the way there.
