Up till now, the TV Nielsens have been ruling the roost when it comes to how many people are watching something. Now with tracking added that includes online content on something of an equal basis, the real TV customers (the people who pay for ads) will know what the product (the viewers being shown advertising) is actually doing. This being Slashdot, people are no doubt running to the store to pay for a roll of tinfoil with a Bitcoin, but it's really not the Orwellian nightmare that you might expect. Imagine if there had been this richness of data for some shows like Firefly that were floundering in the TV ratings, yet were developing a following based on online views -- the audience was following the new episodes, but lagging the broadcast by a few months as they caught up.
I expect that many shows which got mishandled on broadcast yet had some redeeming value and a loyal (young, target demographic market) who aren't showing up on TV lists (because they don't own one) are going to now be more represented -- and that's going to lead to better programming for the people who like that. Perhaps the "sit in front of the TV" market will be eclipsed by the "sit in front of the tablet/smartphone" market as that becomes the way people consume television.
It might also clearly show what many of the cable providers keep denying but don't want to admit -- there's a tremendous market for (effectively) a la carte television that's being consumed right now. They can keep denying it, but it's going to be very hard for them to have leverage in deals with (especially) sports leagues when the Nielsen numbers show that it would be a great business decision to provide an app rather than going through cable to reach a larger audience who is young, hip and spends money.