A dreadnought itself is pretty harmless to cruisers, unless we're talking about the Valor/Redemption/Tokugawa. It can have all the guns it wants, it won't hit with any and it just won't dodge a light mortar. I think that the dreadnought-cruiser problem is more urgent to address than the dreadnought-light/medium battleship problem.
Concerning broadsides and cruisers, I was rather speaking about battleships that can already defeat cruisers using the frontal technique I described.