Every manufacturer is not going to have their own solution. The top few, sure. But it's a different story for the long tail. It can't possibly make sense for all the companies with 1% market share and no notable software knowledge to write their own systems, especially with all the likely regulatory hurdles. It wouldn't be good, and it wouldn't be cheap.
There's clearly going to be a huge market for commodity solutions, and the economies of scale and the network effects suggest that it should narrow down to a few main ones.
Is Google's going to be one of those successful ones? Impossible to say for sure, but they do have a couple of huge advantages. They already have the geodata (all car manufacturers would still need to pay either Google or Nokia for that, even if they wrote their own software). And if I were a car manufacturer, I'd rather not license software from a direct competitor, but from an outsider. It certainly seems worth a bet.