If Ace had survived but WB didn't, I don't think there would be any Whitebeard Pirates without Newgate himself, the captain of the crew. Why would have Ace done? He would have probably tried to fight back the person who killed WB.
The very reason why he was looking for Teach was because he killed Thatch, one of the division commanders. So, there's no way that he would have forgiven the person who killed his captain (OYAJIII =P)
PS: No, in case if people still have doubts, Ace is dead. Lying in the grave. Marco and Shanks literally put him there. So, unless he magically healed the giant hole in his chest and found a way to dig himself out of the grave like those Thriller Bark zombies, he's not coming back.