> Frameworks like WebForms and WCF not be ported
WebForms is terrible and I see no reason for anyone to pull that monstrosity of a "I wish we had a VB/Windows WYSIWYG app-editor for the web" impedance-mismatch into a new codebase.
Applications which haven't migrated off WebForms yet, probably have little to gain by moving to .NET Core anyway.
WCF has been open-sourced[1] and ported (at least the client libraries) and you have separate community-projects[2] working on porting the rest of the stack to be compatible and usable with .NET Core.
If the community really want's to go full WCF on the new stack, they are empowered to do so.
Given that .net is much more entrenched than Python was 12 years ago, I think it going to take a lot longer! Frameworks like WebForms and WCF will not be ported, so projects depending on these will require massive rewrites. This a lot more work than fixing string encodings and putting parentheses after "print".