Yep... I think Apple, Google, Facebook et all are all set for a correction. What strikes me about Apple is that unlike other competitors they have all their eggs in one basket, and they are in every stage of production of their stuff.
Microsoft just make the software, likewise with Google. Samsung have their fingers in many pies... but Apple make the software, the hardware, the retailing, the servicing, and they effectively control the content on it too.
The Facebook rot is already setting in, sure it's going to expand a whole lot more, but where it's already reached full capacity people are getting fed up with it. Add to that they still don't really know how to monetise all that traffic without losing the traffic.
Fashion will turn against Facebook and Apple etc... and that's going to really hurt their share value.