And thanks for trying to question my expertise. Please look up the no true Scotsman fallacy and see if that may apply here.
They share the same DNA in the sense that every cell in that body does. But the different types of cancers have different mutations per cell type and the increasingly precise identification of those is the basis of the recent new treatment options. Histological classifications become less and less relevant, instead mutations and subtypes of mutations give directions for treatment paths. So I think that statement is a bit confusing.
What do you mean by "histological classification" because every interpretation I can think of is very incorrect.
If you mean diagnosing the type of cancer (e.g. clear cell renal cell carcinoma) we've already been using molecular markers for over a decade now.
Since you mention "describing the look": mitotic rate and local staging (depth of invasion, lymphovascular invasion, perineurial invasion) matter far more than any DNA/type of cancer and this isn't changing at all nor will it ever change.