Microsoft has published a new article about .NET 3.x support policy:
Mainstream support phases will end as follows:
- .NET 2.0: 2011-04-12
- .NET 3.0: 2011-04-12
- .NET 3.5: 2011-04-12
- .NET 3.5 SP1: 2015-01-13 (part of Windows 7)
- .NET 4.0: 2016-01-12
- .NET 4.5: 2016-01-12
- .NET 4.5.1: 2016-01-12
- .NET 4.5.2: 2023-01-10 (part of Windows 8.1)
Beginning with .NET 3.5 SP1, the .NET Framework is considered a Component of the Windows OS. Components follow the Support Lifecycle policy of their parent product or platform.