I think there are a whole host of things that sell units.
People like pretty things, and pretty graphics matter when selling $60 games to core gamers. Whether folks know to attribute it to framerates, resolution, or AA isn't the question. Does it look good? Does it look noticeably better than the other? It can drive desire. How much better can Sony's games look than MS's? And will they arrive in time before general perception is made?
Gimmicks matter. They're tricky because you can't necessarily do the same thing twice, but you can capture that same gimmicky spirit. Motion controls brought in casuals and then they fell out with it. Kinect is doing/will do the same thing. I'm not convinced a 2.0 can be conveyed as something different to them....think Wii Motion Plus. I think you need rumored Occulus Rift type headmounted stuff to have a possible crack at that market again. At least to get them to buy into it droves.
Services/Awareness/Loyalty. Everyone's called for it and more and more evidence suggests this will all be about services. Based off rumors, I expect the new Xbox to remind you about the airing/recording of Breaking Bad, while you're playing Halo, after you've programmed it to do so on your tablet or whatever. They're going to try to sell us on that, and ride the momentum they still enjoy right now. That positive momentum is their trump card in my book. When you're in the store of BestBuy or GameStop, you don't fully see the services in action. You'll glide over the UI, have a subconscious verdict over the UI-style and go for the games.
A new cycle, I would imagine is a time when everyone's willing to see what the competitor is doing. They'll look it over. They may have a preference going in, but they'll check out the competition. And that's where Sony has to make its move. It has to have the games available to show the difference. They need to look a step ahead or look more interesting...and/or be more plentiful. if it looks comparable, people stick to what they know or go for the cheapest. it all comes down to the games at the start of these cycles to me...and then its upheld by direct/indirect peer pressure. This is when purchases are asking the most questions, are doing some form of research.
I think Sony can make inroads just by releasing timely and having games available at launch unlike last time. I think they'll be neck and neck despite specs, and that MS loses some market share just by way of Sony being out the gate at the same time.
