He no longer had the entire Nova Force as of the end of the extended Annihilation storyline, but he did become Nova Prime once they reformed the Nova Corps (which would mean he has access to a larger chunk of the pie than he used to as a regular centurion, so he was still buffed up compared to his modest power levels pre-Annihilation). But admittedly, I don't really know what all happened to Richie after the whole Cancerverse storyline, because I'm a liiiittle bit behind lol
But I do specifically remember there being a new Nova Corps after Annihilation, and for that to happen Richie would have to have split the Nova Force back up again to give the other centurions their powers.
EDIT: But you know what, I do think he still had the Worldmind for a long time after Annihilation, so maybe that's where we're getting mixed up? I need to reread that general batch of Cosmic Marvel anyway, it was a good set of storylines from Annihilation up through Thanos Imperative.