Would the unbuilt Admirals form a Hood subclass?

Would Anson, Howe, and Rodney have been members of their own subclass within the Admiral class?

Probably not merely a subclass: Hood and the later ships would likely have been treated as separately named classes.

The projected Anson, Howe, and Rodney probably would not have formed a mere subclass beside Hood. Their design differences and naming practice would have separated them more clearly. Hood could have anchored a Hood class, while the first completed follow-on might have lent its name to the later group. A programme's administrative umbrella does not always predict the class names historians would ultimately use.