Thanks for the feedback Yuhong. As you correctly pointed out .NET 2.0 SP2 and .NET 3.0 SP2 are sub-components of .NET 3.5 SP1 so it makes sense to have these on the same lifecycle. The good news is that this is already the case, the Knowledge Base Article 2696944 clarifies that when .NET 3.5 SP1 is installed the same lifecycle will apply to .NET 2.0 SP2 and 3.0 SP2 too.
This is the relevant snippet from that KB article -
...snip...
However, Microsoft will provide support for the .NET Framework 2.0 and .NET Framework 3.0 components for customers who install the .NET Framework 3.5 for as long as the .NET Framework 3.5 remains in support.
...snip...
Thanks,
Jamshed
Program Manager, .NET Framework Fundamentals team
This is the relevant snippet from that KB article -
...snip...
However, Microsoft will provide support for the .NET Framework 2.0 and .NET Framework 3.0 components for customers who install the .NET Framework 3.5 for as long as the .NET Framework 3.5 remains in support.
...snip...
Thanks, Jamshed Program Manager, .NET Framework Fundamentals team