Returning the Same Type with a different inner type

[TonyValenti]

I know my syntax is wrong, but how would I do something like this:

        public static TParent<TNew> WithScope<TParent, TOld, TNew>(this TParent<TOld> This) where TParent<>, new() {
            return new TParent<TNew>();
        }

        public static void Main() {
            var Data = new List<long>();
            var Data2 = Data.WithScope<int>();

        }

Generate a method that Accepts a TParent and returns a new TParent?

[Joe4evr]

I believe this is a scenario that requires Higher Kinded Types: #339.