public class ViewModel : SomeBaseClassForINotifyPropertyChangedAndOtherCrap
    {        
        public object View
        {
            get { return _View; }
            set
            {
                SetViewData(null);
                _View = value;
                SetViewData(this);
                OnPropertyChanged(() => View);
            }
        }
        object _View;

        void SetViewData(object model)
        {
            if (View == null)
                return;

            var iView = View as IView;
            if (iView != null)
            {
                iView.Data = model;
                return;
            }

            var frameworkElementView = View as FrameworkElement;
            if (frameworkElementView != null)
            {
                frameworkElementView.DataContext = model;
                return;
            }
        }
    }

    public class ViewModel<TView> : ViewModel
    {
        public ViewModel(bool createView)
        {
            if (createView)
                View = Activator.CreateInstance<TView>();
        }

        public ViewModel()
            : this(true)
        { }

        public ViewModel(TView view)
            : this(false)
        {
            View = view;
        }

        public TView ViewAsT
        {
            get { return (TView)base.View; }
            set { base.View = value; }
        }

        protected override void OnPropertyChanged(string name)
        {
            base.OnPropertyChanged(name);
            if (name == "View")
                OnPropertyChanged(() => ViewAsT);
        }
    }

    public interface IView
    {
        object Data { get; set; }
    }

class MyUserControl : UserControl
{
     public MyViewModel Data
     {
          get { return (MyViewModel)DataContext; }
          set { DataContext = value; }
     }
}