I like Rhianna. Her work on the Overlord games has been superb, and her story for Divinity was very good, too.
However - there's only one Terry Pratchett. I hope that if Rhianna does become a full time novelist she will create her own world(s) rather than continuing with the Discworld.
No insult at all meant to Rhianna, but Discworld is too uniquely one person's vision. I can't see any other writer being able to continue it.