Just wanted to mention that nothing in that article supports it's title, or your title mentioning "self-driving suite concerns".
It does have quotes from Musk saying that Vision is better than Vision plus radar(normal radar), and separately that Vision plus High Definition Radar would be better than Vision alone... Nothing about any "concerns".
And only way there would be a retrofit would be if it is required for FSD. I think it would be more likely that the cameras would need to be upgraded before needing an HD radar component.