[Blazor] Obsoleting TreeRouter in .NET 9.0

[javiercn]

At this point we've been shipping endpoint routing for 3 releases, which uses the new DFA matcher. There are a set of routing components that we no longer use and that is unlikely someone is still using. (All the TreeRouter and related implementations) we should consider obsoleting them in 8.0 so that we can remove them in 10, as we are not going to use them anymore and people should not be depending on them.

The reason is that we reuse these implementations in Blazor and it will simplify our lives a bit if we could just reuse them in place without having to ifdef the code.

[danroth27]

It's pretty late in the release to do this. How about we do this early in the .NET 9 release and see what user feedback we get?

Thanks for contacting us.

We're moving this issue to the .NET 9 Planning milestone for future evaluation / consideration. We would like to keep this around to collect more feedback, which can help us with prioritizing this work. We will re-evaluate this issue, during our next planning meeting(s).
If we later determine, that the issue has no community involvement, or it's very rare and low-impact issue, we will close it - so that the team can focus on more important and high impact issues.
To learn more about what to expect next and how this issue will be handled you can read more about our triage process here.

[javiercn]

Moved this to .NET 9.0