Certainly 16GB on the floor is certainly nice but I would probably still opt for a 256 drive that I could add up to a 512 Gb with an SDXC micro.
I was thinking however, that the recently available 4.5 watt fanless Broadwells with a 2GHz base freq turbo'd to 3.0Ghz would be helpful. And with a Broadwell in the same form factor as the current SP3, you retain the use of the current MS Docking Station etc and get 25% more life (so Intel says) off the battery that already exists, though I suspect better/bigger batteries may be available for the slightly larger space afforded by going to a fanless 14nm chip vice the current 22nm fanned iCore 3, 5, 7.
Were I Panos Panay's team I would not opt to change much else. We could argue about additional USBs or switching from MDP to HDMI or whatever ... but the design compromises already made we have all adapted to. And changing them inserts additional hardware and software risks that we just can't afford to take when we also have Win 10 to adjust to at the same time. You do get a bit of a graphics boost with the Broadwell's associated GPU, but once again I would not change much to accommodate 60FPS gamers, for example, when the machine is more general or business oriented. OTOH I could see trimming the blacken screen around the bezel maybe back about .25" and that would give us an effective screen size of close to 13 using the same form factor and use the upgraded GPU to power it with the same pixels per inch at 3:2 as is now the case.
Just my $00.02