Xamarin developers will still be able to develop their legacy projects with Visual Studio

[maddymontaquila]

Projects using storyboards for iOS, XML for Android, and XAML for cross-platform will still be supported using the existing Visual Studio capabilities. Conversion support to SDK Style projects will be provided via the CLI TryConvert tool, and developer guidance will be included for code migration.

[Aguilex]

Xamarin Tools comments... this is considered mostly a "regression testing"... existing projects need to continue to work. This implies that the iOS and Android SDKs will continue to be inserted into VS and VSMac as done today.