This already exists, ex. Audimee: https://audimee.com/
RVC is so easy anyone can spin up a website for it. No moat. Over a hundred thousand trained weights files in the open, so it's easy to bootstrap.
"The RVC model is a Retrieval-based Voice Conversion system using AI for high-quality voice cloning. It utilizes artificial intelligence to modify or clone voices in real-time." Source: https://speechify.com/blog/rvc-vocal-models/
Would make a nice vignette in a film about a dystopian future where video can be be generated cheaply and of sufficient quality.