The reason Shell _could_ drill in the arctic is because the US okayed them doing so in the form of leased drilling rights. And more such leases were all set to go up for sale. However, since Shell was the only player and they folded, the US has decided to cancel the proposed lease sales.
Of course, the thinking is that One Day, oil will be expensive again, and it will make economic sense to do crazy shit up in the cold and dark to get at it to sell to our guzzling cars, homes and industrial operations. We can't be sure that oil will _never_ be extracted, or even be sure what the next president will do in terms of selling the rights to try to extract it.
But for right now, I'm pretty happy about this news. And you never know, battery tech is slowly improving, California utilities are signing up for more storage deals than they are required to do -- maybe it won't _ever_ make economic sense to drill up there in the cold and dark. (ETA: http://tdworld.com/smart-grid/ge-signs-its-largest-battery-energy-storage-deal-date)
ETA: Lisa Murkowski is, predictably, peeved.