Doesn't Skylake include USB3.1 ?
A significant speed jump over USB3 ?
Skylake will enable the use of USB-C ports that also support Thunderbolt 3. That in itself is a reason to wait. It will bring alot of great features in the future. Companies during CES showcased many usb-c compatible screens, hubs, docks etc. so we know the industry is already adopting USB-C/Thunderbolt in its infancy.
And due to Thunderbolt 3 you can connect practicly anything to the port (if compatible).
But a message to the OP, if you do not do a lot of gpu/cpu intensive work (video editing, programming, 3D modelling etc etc.), then just get the current model. Its fast, reliable and a great machine. Performance improvements will be minimal and unnoticable if you dont run heavy programs.
I can only think of 2 reasons why you should wait for Skylake if you don't max out your cpu and/or gpu
1.
Connectivity. The implementation of USB-C/Thunderbolt 3 will bring a lot of new products and features and there will be a massive switch to the port. So having the newer model will offer you modern connectivity throughout the coming years.
2.
Battery life. Skylake will support DDR4 RAM and it will have the integrated Iris Pro 580. Both of these elements will be faster than it's previous versions and it is more energy efficient. Hello longer battery life
(albeit 1 hour or so longer)
Hope this helped