I think it is indeed a turning point for the A380, and the beginning of the end for the B747-8.
For example, on London-Hong Kong Cathay will have been looking to see what BA are going to do. Now BA have confirmed they will go for the A380 (and Cathay will be able to work out that the 12 ordered will include the Hong Kong route) then they will feel they need the A380 as well to compete effectively.
Similar approach elsewhere. South African may not have much funding currently available, but if they can't compete with BA they probably feel they are finished on the London route. Japan Air Lines are probably having a long think this morning as well.
BA have no need for an aircraft fleet sized between the B777-300 and the A380, let alone one whose basic design concepts are in the 1960s, so it does seem the end of the B747-8 is closer. What on earth possessed Lufthansa to buy them ?