ソースコード

public static class NullableExt
{
    public static void Deconstruct<T>
    (
        this T?   self,
        out  bool hasValue,
        out  T    value
    ) where T : struct
    {
        hasValue = self.HasValue;
        value    = self ?? default;
    }
}

使用例

var now = DateTime.Now;
var ( hasValue, value ) = new DateTime?( now );

参考ツイート

Here's an extension method for you leveraging C# 7.1. Deconstruct any nullable into a tuple! #csharp @dotnet pic.twitter.com/yPNR8XYlbW

— 🅳🅰🆅🅸🅳 🅿🅸🅽🅴 (@davidpine7) December 15, 2017