Microsoft pulled it off with dotnet, sort of, because they approached it like a completely new language, sold people on the benefits of it.

And the people they were selling that to, ( It's free and open souce now! ), were a very different group to the market they left behind on .NET Framework, who are often still struggling to make the transition now.

Had they actually killed off .NET Framework, it would have been a different story, much more like the VB6/VBA to VB.NET transition, which so few people bothered with that VB.NET died out, because if you had to retrain that much, you figured you might as well go to C# or a instead, or indeed a completely different language entirely.

I briefly worked professionally on a VB.NET project, but outside that job I've never met anyone else who can say the same. I've met a few who went straight from VB6 to C# though.

Both of those were a vendor X electing to stop updating framework A in favor of framework B. That’s a high cost for vendor X’s users, but if their business depends on vendor X, they have no choice. Maybe they can switch to vendor Y at that point, but now you are switching both vendors and frameworks.

Replacing CUDA with another framework has much lower motivation. That advantages of the new framework must cover the switching costs and the risk of such a switch. All while CUDA continues to evolve and allow access to additional features.

Apple and Microsoft had something of a captive userbase. New vendor on the block trying to replace CUDA does not.

Neither of those are a competitor replacing another, they are a same-vendor replacement. This is easier, because the company whose established product you are trying to displace is cooperating (because its you!) not actively resisting.

Anthropic rewrote Bun in Rust, with much help from AI of course