Every developer I know who has adopted Blazor never wants to go back and touch JavaScript. If you do it right, it will sell itself, your market isn't people who use React exclusively, but people using Python and possibly react, but also any other web framework. IMHO the key thing would be a standard similar to WSGI for this system, so it can be implemented and supported by any web framework. ... the more I think about it, the more I am going to have to look at writing a draft PEP...
But the ecosystem of React, including UI libraries, charting, forms, and so forth, is enormous.