Yes this is a purely hypothetical situation... But should the situation exist the player will certainly win more often than the dealer... And I mean WAY more than 50.x%. Think about... If the dealer shows an ace as his up card, there is virtually no way the house can win unless the player makes a mistake. After buying insurance, either pair would be split and resplit to the max if he doesn't have it. Similarly, if the dealer shows a 10 and doesn't have it, either pair would be split and resplit to the max. And finally, if no player pair, there is no way he can lose after the dealer has checked his hole.