Nvidia's fief has a lot of folks in it, who've built sloppy stuff all over the place because they can. Most of that won't get replaced.
But the modern tooling like PyTorch and its underlying JAX doesn't need or care about this legacy. The future can build far more intimately & with deliberation to folks who haven't such large swamps around their ecosystems. We can tune systems more efficiently & carefully when our vendors don't keep us so so far away from the core hardware. Nvidia has to keep maintaining this huge footprint of software, keep it going themselves, supporting a vast legacy, while everyone else gets to innovate forward, with much better access to the hardware.