I think to the extent that data is stored over a period of time by, say, an advertiser advertising in a digital format, the pseudonymous data will be maintained over time. The opt-out is typically forward-looking, and in the future they're no longer going to conduct online behavioural advertising.
I think that to destroy all data retroactively becomes a pretty significant challenge. There are people who are far more articulate than I, but I might point the committee to some of the discussions going on in the European Union regarding the right to be forgotten.