If you could change one thing..

[a-m-k]

I'd make the hinge smaller or quite possibly design the screen and keyboard so the screen closes (the hinge) from behind the keyboard.

 

[eastercat]

User upgradability, more USB ports
As a vegan, I think the computer is lighter than comparable 15" machines

 

[K-Line]

make it expandible again (no solded ram no proprietary ssd no ram limit to 16gb)

that's why I didn't have bought the rMBP but the used MBP instead

 

[alaaf]

I would change the users behind the keyboard

 

[2984839]

I have a list of things for my early 2011, so take your pick.

Either add a USB port or add more space in between them. I often cannot use both USB ports at the same time because they are too close. Some fault lies with the manufacturers of the USB devices for being greedy with the size of the dongle, but Apple put them too close. Plus, a $1500 machine should have more than 2. Even my $400 Vivobook has 3.

I would also like a smaller bezel and a keyboard that extends to the edge, like the 12" PowerBook. The footprint of this 13" model is a little big and it doesn't leave much room on university desks for a notebook.

I would rather have HDMI than either Thunderbolt or FireWire. I don't care which one it would replace. I hate Apple's "Just buy an adapter" culture. It's ridiculous to have to spend $30+ on an adapter to get basic functionality like HDMI from a $1500 computer.

 

[yangchewren]

Not dreaming too big here, even this choice would be a difficult one:

1. Have a higher wattage power supply with SMC to match

2. 850/860m as mentioned earlier

 

[Cloudsurfer]

Ehh. The lower power consumption means Apple keeps the same battery configuration and touts longer than the last generation usage times on the next generation MacBook line.

No it doesn't. It means they have an excuse to shrink the battery and keep the same battery life as before. They've been doing this for years. In fact, the battery life has even slightly decreased over time.

My 2010 MBP was advertised as having a 10 hr battery life, today it's down to 8-9 hours with much more efficient components.

If Apple does keep the same form factor as before, it's more likely they'll opt for faster CPU's over longer battery life. Especially the 13" could use a power boost.

 

[capuzino]

13" rMBP (2013):
- User upgradeable RAM, I'm running out of 8GB and the magic of the memory compression (which really is like magic!) quite easily
- Iris Pro graphics (or better)
- Integrated SIM slot for LTE
- Thunderbolt docking station (for extra USBs, HDMI and optical in -audio) as a standard peripheral

- Hope they will keep the SSD upgradeable in the future too.

Software:
- The greatness of BetterSnapTool integrated
- In Yosemite option for the old Mavericks like UI (for icons and dock at least)