Yup, there will be bits and pieces, and groups of other races, and so forth scattered about... Tyrlon is basically where everything ends up when you get uncontrolled portals, magical rifts, and so forth. It isĀ basically the garbage dump of the universe, so to speak.... so there is no telling what will end up there (and what might possibly survive...)
The main city is actually a colony. An Elven prince and his retinue (several ships worth), accidentally found it, and then figured out how to leave (and more importantly how to return, on purpose), and decided to basically set up his own kingdom/colony.
This will let GMs pull in characters from almost ANY game setting that he might want. Plus, He could even have characters travel from Tyrlon to other game settings and return via the dimensional storm that surrounds Tyrlon.