If they truly make it opt-in then that's good! Opt out, as can be seen and has been noted many times, is far from a panacea to give people any solutions to the ongoing data harvesting and privacy nightmares. Everything should be opt-in, removing the onus on users to take endless measures needed to stay ahead of the curve.
The only thing that matters to me is that I don't get to see any warning about stupid cookies, it's the dumbest thing ever, the person who came up with this should be in jail. I mean who cares about 1st party cookies anyway? Just make sure you block third party cookies.