It is always interesting to hear what features people see as key to a product, for me the 3 biggest G factors are the small sensor, ability to hook up my existing flash kit and fit supplementary lenses.
The small sensor gives me the depth of field I want, need and use, increasing the sensor size would significantly alter and change this characteristic, the market is flooded with larger sensor models - improve it, get better resolution, higher ISO but please, please, please leave it the same 4.6x factor!
While the camera is small, being able to hook up all my existing flash is also extremely useful, while Canon flash technology is getting a bit long in the tooth - it does work and works very well. So I regularly hook up 1, 2 or even 3 large EX guns, use wireless, slave and master features, ratio control, light stands, brollies, etc.
The ability to fit filters, supplementary lenses is also a great feature, it enhances and extends the capabilities, it is one of my killer features.
I love the size, big enough to hold, but not too big. I have a love/hate relationship with the ergonomics and the multitude of small buttons which always get in the way.
What I would like to see is a longer zoom, improved sensor/higher ISO, built in flash controller, longer exposure than 15" or possibly more important give us a bulb feature to allow longer exposure, improve the optical viewfinder, upgrade the rear screen - confirming focus when doing close up is a real pain, ability to hook up to a larger screen such as an iPad, but upping the shooting rate would be good - I don't need 8 frames per second - but 3 would be nice, that is off the top of my head, I am sure there are others.
The G has been a very popular and hugely profitable range, combined with being a quite distinct market segment, I think it should/will continue, but what do I know. We will possibly get a unit that does amazing 3D video and allows you to connect remotely to a printer - hmmmm, what do they say "be careful what you wish for" and do they sell what you want, or what they can make...