I've recently picked up a 15" MacBook Pro mid-2015, i7 2.5GHz, 16GB Ram and 256GB SSD. It's in excellent condition. I know that with a lot of MBP's these days they are 'un-upgradeable' due to parts being soldered in. However, I am wondering whether in the future the SSD would be upgradeable to a larger one (1TB?) with this machine?