I think Adrian should jump into the conversation. He does it all the time in his blogs.
Here I am. So...
1. I am not doing a damage control, but I do want to clarify one thing. But first, yes, devs I know -- and as someone has shown it before in this thread, some other devs already talked about it too -- claim that there's 50% speed difference WHEN DEVELOPING in cross-gen/next-gen PS4/XO games. So there we are, I said it and I stand by it. Notice: WHEN DEVELOPING. It'll become clear in a second.
2. Will this change in the future? WIll devs discover some tricks to narrow the gap? Will stuff like XO cloud computing help? Hell if I know. Uhm, maybe? I know that devs -- well, most of them -- will do whatever they can do get you the best games possible. You're going to see a lot of multiplatform games this next gen, just as you've seen them in this gen, so it's in studios' best interest that there's no clear advantage in one version over the other.
3. Does it mean studios will cripple PS4 versions to match XO ones? Not really, do not underestimate the devs. Even if this happens, you will not know that and that's okay. You've never seen most games in their most powerful form anyway (when we work on them on our ninja dev PCs in 1080p 120fps with all the antialiasings and stuff turned on for shits and giggles). But most of the time devs have a target and they meet this target. If it's a multiplatform game, it's designed with this in mind from the start. So maybe it's not maxing out one console while going 100% on the other. Maybe it's 100% on both, but they take extra time for super-extra optimizations on the weaker hardware to make sure things look the same as on the more powerful platform. Etc. etc.
4. So what is that "one thing" I want to clarify, that some people may consider "damage control", but really is just an explanation. Someone mentioned Titanfall, which looks money and enjoys a great hype. Exactly. A great dev will make a great game no matter what's the hardware. Current gen CoDs looks great and it's 60 fps, on both platforms (well, and PC :). To most devs that is just impossible to achieve. And yet...
Think about it this way. X360 is faster than PS3. Not just easier to program on, it's faster overall (although PS is faster/better in SOME areas). And yet no exclusive on X360 looks like The Last of Us. Halo 4 looks great. Gears blew my mind in 2006. And still, the best looking AAA game of this generation belongs to the supposedly weaker platform.
So if you think that the war is over because PS4 is 50% faster TODAY, then you're delusional. This is far from over, and will probably never be over, at least not this upcoming gen.