UI Design is a type of language and as such has to communicate a symbol with a meaning (or action in most cases).
If you can use a language element that your user already understands, why would you rule it out?
I also wonder why you compare Skeuomorphism with flat design when you can have a flat skeuomorphic design anyway.
And I'd also be careful with stating that any design trend is here to stay. Most design trends have been here before and will be back again in the future. It just happens that the flat-look is on trend.
If you can use a language element that your user already understands, why would you rule it out?
I also wonder why you compare Skeuomorphism with flat design when you can have a flat skeuomorphic design anyway.
And I'd also be careful with stating that any design trend is here to stay. Most design trends have been here before and will be back again in the future. It just happens that the flat-look is on trend.