Google doesn't make hardware and software, they don't control the whole device. That's the main reason the credit cards would decide to play ball with Apple.
For the rest, I respectfully think you are confusing what is actually happening here. Tokenisation does not mean that that different formats of information are trying to be passed to the NFC reader. It means that a different set of data is substituted for the sensitive information, but delivered in the dame format as the NFC reader expects it. This token is decoded by the credit card companies back to your card number and approved.
So it doesn't matter how tokenisation is implemented, if at all, by different implementations, ie Softcard, GoogleWallet, or

Pay. They all have to use the same format that the NFC PayPass PoS terminal expects in order to work.
It would be EXCEEDINGLY stupid for Apple to try to implement their own standard for this communication other than NFC and try to push this proprietary standard on retailers, requiring them to have a separate PoS just for

Pay. It would be an instant and comical DoA proposition then.