He may not have the wand yet, but the symbol of the Deathly Hallows already featured heavily, providing those implications. But yeah, I think the world is strong enough to support a lot of stories and Rowling a masterful enough world-builder to make them strong. Notably, it seems she was slightly less involved in the play currently on the West End (which I wasn't a huge fan of in script form), but is more centrally involved with these screenplays (as the sole credited writer).