People who have 060 cards are people who tend to have more than one Amiga, too. Like me (except I don't have an 060 card). I have an Apollo 3040 in my A3000. If i got a V3000, that Apollo would move into my A4000, thereby pushing an A3640 onto the market.
And I think that's what would generally occur; Vampire 1200 cards would result in 1260 card being put into the second A1200 of Vampire owners, thereby pushing a lot of tired old 1230 cards onto the second-hand market.