I won't say anything about retiring MCSA/MCSD/MCSE certifications that are still required today like Windows Server or SQL Server since there are a lot of comments about this questionable move from Microsoft. But i will argue about retiring exam 70-483 about C# and exam 70-486 about ASP.NET, it can be acceptable if you are planning a .NET Core version of those certifications, but nothing have been announced about them. Isn't Microsoft developing a .NET 5 and .NET 6 with MAUI? So why retiring those certifications? All the effort of the professional community to get certified will go to waste, just like it happened with the Xamarin certification that you didn't even release a purely Microsoft-made cert. Retiring a certification of a core Microsoft technology like C# or ASP.NET is like saying that those technologies aren't that important and are useless. It happened with Xamarin certified developers that demand dropped and no one cares about it, companies just prefer to go native.
Since a company like Microsoft isn't going to back down, I still hope they consider releasing a new version for the .NET stack, for C# and ASPN.NET, and maybe about MAUI that can be the new Xamarin. There are still developers that want to get certified in .NET because of their jobs requirements. Or maybe just because they grown up learning Microsoft technologies like vba on office apps or visual basic 6.0 and want to prove themselves with a cert of a technology they used since long time ago. I'm one of those developers.