yeah but all your internet traffic would then be throttled. Not just certain services. Using a VPN essentially takes away everything from them and reduces their only tool to a hammer and forcing everything to look like a nail. There is no granularity. All your traffic goes to one location. They can't see what it is or what the final endpoint is because of encryption. So they can't use it to build a profile/data on you to sell. They can't inject ads into HTML or block services that compete with their own, or even grant privileged speeds to approved or preferred services. They basically are forced into a Shakespearean "to throttle or not to throttle" binary choice.
That's true, but in practice most consumers wouldn't notice. That's because the whitelisted services would most likely include those data-hungry services used most frequently by consumers: Netflix, Hulu, YouTube, Facebook, etc. which are operated by big providers. This was how Comcast operated in ca. 2013.
The bet is ISPs would be very comfortable throttling traffic, as long as whitelisted services were not affected. (They see this as a revenue generator, because they can sell fast-lane access to companies who don't want their customers' bandwidth throttled.) ISPs that go this route will likely offer a (consumer-paid) option to allow VPN traffic to use the fast lane.