I would imagine the only companies that would make use of this are those with locked down ecosystems. I can't see Acer, for ex, caring much - if anything it saves them support costs when the warranty is voided by rooting.
Granted, the largest players are those who also sell / control content, but as I can access all my Amazon content on my tablet quite easily and legally, I don't need a Fire to use the ecosystem anyway. iOS is the platform with no other options in terms of alternate hardware, but the majority of my iFriends aren't interested in jail breaking their devices anyway, and I wager that is true for the majority of users.
The devices most likely to be jailbroken or rooted are those which are partially subsidized by projected future purchases, like the Nook or Fire. But I can't see amazon sending people to jail. The backlash would be immense if they did. B&N are an unknown now that they are partnering with MS. Not sure how they would proceed.
So, while I'm not pleased with any of this, reality (combined with the fact that they can't decide what a tablet actually is) seems to be that this is mostly language meant to dissuade via criminalization. It relies on the companies themselves to use the correct TOS / license language and to monitor their respective ecosystems for hardware in violation of that language and then initiate action against one of their customers. I suspect few would.
I suspect Google may be modifying their partner agreement soon. Just a hunch.