I would suggest adding, not replacing, the target for net8.0, because .net 7 projects will grab the netstandard version if there's not a package targeting 7.

And actually, unless it causes build errors, dropping 2.1 to 2.0 will enable framework projects to load the netstandard version as well. 2.1 was for Mono and added some goodies, but didn't get backported to .net framework.

If that does cause build errors, then of course leave 2.1 there for Mono peeps.

But we probably shouldn't be breaking compatibility with existing systems for any changes made to v1 til it's fully retired.

And adding multiple TFMs, if not build-breaking, costs us nothing. If an actual runtime issue crops up, we get to just say "sorry - not supported on EoL SDKs. Use at your own risk."