I'm very worried about RAM really, storage will sort of take care of itself as data connections become quicker and storing files at home and pulling them down to your laptop on the road becomes commonplace. The RAM is just a massive sticking point for me - I started off with my current MBP 13" in 2009 and it came with 2GB RAM. Since then it's been upgraded to 4GB and then 8GB more or less on the anniversary of its purchase.
I like Mac laptops because every one I've had has served me well for 3 years before I've sold it mainly because the Applecare expired and I didn't want a laptop without a warranty. But to predict how much RAM I'm going to need in 2015 is an impossible task.