I think the RAM idea would be better than using some kind of cartridge, though. We all know third-parties aren't going to be happy if the medium for the system is any more expensive to manufacture than competing systems, so they can't use cartridges if they want support.
I actually suggested it as a joke, but after thinking about it some, it actually kind of sounds like a good idea. It lets them still use discs but eliminate load times, plus people wouldn't have to go through the hassle of installing games onto a hard drive or equivalent. The only issue is manufacturing costs for the system. I've heard that RAM is fairly cheap these days, but most computers don't have more than a few GB worth. How much would, say, 25GB of RAM cost?