Even Silverlight is not officially dead until 2021 so I'm not sure I'm clear on your terminology (vs. https://support.microsoft.com/help/17455 ).
Just for fun I dug up the "Mainstream Support End Date" for ASP.NET on .NET 4.5.2: 10/9/2018.
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Starting from https://www.asp.net/support
Many parts of ASP.NET are a part of the Microsoft .NET Framework, these include ASP.NET Web Forms, Controls, Modules, Handlers and more. For more information see .NET Platform Support.
Then at https://www.microsoft.com/net/support
The Support Lifecycle information for all versions of .NET Framework can be seen on the Microsoft Product Lifecycle site.
Then at https://support.microsoft.com/en-us/lifecycle/search?alpha=....
For more information, please visit the .NET Framework Support Lifecycle Policy FAQ.
Then at https://support.microsoft.com/help/17455
Support for .NET 4.5.2 follows the lifecycle policy of the parent operating system. It is supported as a Windows component on the latest required operating system update for Windows Vista SP2, Windows 7 SP1, Windows Server 2008 SP2, Windows Server 2008 R2 SP1, Windows 8.1 Update, Windows Server 2012, and Windows Server 2012 R2.
Then at https://support.microsoft.com/en-us/lifecycle/search?alpha=W...
Products Released: Windows Server 2012 R2 Standard
Lifecycle Start Date: 11/25/2013
Mainstream Support End Date: 10/9/2018
Extended Support End Date: 10/10/2023
Service Pack Support End Date: [empty]
Notes: Mainstream and Extended support for this product has been extended to provide customers with the standard lifecycle transition timeline. For up to 6 years of additional support beyond Extended Support, please see the Premium Assurance website.