(Doubtful as I still am about HS2) I don't think HS1 and HS2 make a fair comparison. HS1 removed a small number of Eurostar workings from an already overcrowded and very slow network. This obviously created some more capacity by removing the need to provide the "long" non-stop EST paths each hour, but not a huge amount. HS2, on the other hand, when it reaches Crewe will take the principal Birmingham, Manchester, Liverpool, and Scotland trains with their long non-stop runs off the London-Crewe portion of the WCML and will thereby create very considerable extra capacity which can be used to provide intermediate centres with a much better service than they get today.
Unfortunately we have no clear ideas yet as to what "HS3", if any such thing is ever created, is going to be and so no ideas as to what its implications for capacity and therefore for improved intermediate services is likely to be.