There are several theories on why he left the internet, from his taking down videos off of the 3rdeyegirl YouTube page, Twitter gone, Instagram gone, Facebook gone. If fans remember the last time he left he really didn't, he released "Extraloveable" on iTunes, there was the jazz version of "In A Large Room With No Light", "Purple & Gold", "Hot Summer", "Rich Friends", and "Cause and Effect". So through it all he has maintained some presence on the net.
Now in 2014 With 2 new albums out, maybe a Purple Rain 30th Anniversary Release, him leaving the net now doesn't make sense. We really shouldn't be surprised this has happened let's be honest this isn't the first time or the last that Prince has done something to raise our eyebrows. Maybe some of the rumors are true that we've heard or maybe he is getting ready for a new campaign. 3rdeyegirl.com still has social media links that are still there although dead you would think that they would be deleted, there YouTube page still up with no videos. These things are easily deleted and done with if he was rejecting the net again, he's leaving traces he is not.
Plus with all the young talent he's working with they haven't deleted there social media pages so I think it's highly doubtful that he has left. I think there is more to come hopefully and His Royal Badness is trying to do something else to connect with us and bring us a much more enjoyable experience.