When I said 'no one', that was an exaggeration, both Knack and DriveClub will sell at least one copy I'm sure.
But okay, if we take a closer look logically, who is going to buy those games. You mention parents buying a PS4 for their child. This will happen, there will be young people who get PS4 this holiday season, how young do they have to be for Knack to be their preference? I'm going to say 8ish? How many eight year olds get a brand new system the holiday it launches? Especially when it involves preorders and long queues? Probably an extremely low number.
Secondly adults buying one who also just want a kid friendly game. This is going to happen, but even then, Knack becomes a secondary purchase. And if the demos are anything to go by, Knack is going to review poorly, which will affect sales by this sub-set of early adopters.
DriveClub. I can't really think who's going to buy this. Only really uniformed buyers who don't know there's a PS+ Edition for free, and they need PS+ this time around. There will be a number of driving game enthusiasts who are buying PS4's this holiday, and some of them will be woefully uninformed, and till pick up a copy, but again, that's going to be a very low number.
Neither of them will ever sell 500K.