There are some things I feel people aren't willing to consider. First, there were people that purchased the PS3 as a relatively cheap (for the time) Blu-Ray player. My girlfriends parents actually did this. They purchased 2 PS3's (one for her and one for the living room), but she was the only one that used it for gaming. Second, I think everyone assumes here that the PS3 without the cell would be just as powerful as the 360, but what people forget is that the 360's GPU was much more powerful than the PS3's, and that the PS3 offset this by using the Cell processor. It's entirely possible that, like the PS2 vs the Xbox, the 360 would be the best hardware.
Then there are other factors. At the launch of the PS3 there was a shortage of Blu-Ray drive materials, but this obviously wouldn't happen if they would have taken that out. Also, they cut costs on the PS3 later models by reducing backwards compatibility, but they may not have had to do this if they didn't have the Cell or Blu-Ray. Which could have impacted PS2 sales a bit, driving the hardware more towards the middle (e.g. PS2 at 130M, PS3 at 100M). Also, the 360's CPU was based around research from IBM surrounding the Cell processor, and is actually modified from that original model, so it's also possible that the 360 would have had a worse CPU in the final product.
So, this is what I ultimately predict. A 20M gain on the PS3, a 15-20M loss on the 360. A 20M loss on PS2 sales, though Wii sales stay the same. However, this also goes towards the future. Less 360 presence in America and Europe means Microsoft tries harder with the Xbox One. Hardware with that console is much more powerful due to a lack of arrogance, and no DRM fiasco. This leads to slightly more sales for the Xbox One, though PS4 still ultimately surpasses it.