O .NET Framework 4.6 remove a necessidade de todas as versões anteriores do .NET?
Depende de como os aplicativos que usam o .NET são criados.
Some changes in the .NET Framework may require changes to your app code; see Application Compatibility before you run your existing apps with the .NET Framework 4.5 or later versions.
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In addition, if your app targets version 2.0, 3.0, or 3.5, your users may be required to enable the .NET Framework 3.5 on a Windows 8 or Windows 8.1 computer before they can run your app. For more information, see Installing the .NET Framework 3.5 on Windows 8 and later versions.