Mythic Beasts have been offering v6 only for years on their virtual and dedicated hosts - I've got a VPS with them with only v6, no point in paying for v4 if I don't need it.
They point out that offering v4 as a separate line item leads to conversations with accountants about "what's this line item, and do you actually need it?"
They point out that offering v4 as a separate line item leads to conversations with accountants about "what's this line item, and do you actually need it?"