I dont see it. This will only happen if the gaming segment stands still (thus performance requirements), with the occulus and clones coming out, rebirth of VR and augemented reality, holographics, 4K gaming, whatever.
That an IGP should be "good enough" is about analog to the reasoning that 640K should be enough for everyone.. And it would be enough... if innovation stood still. Thank god it does not

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Are you arguing IGP from the perspective of desktop or mobile? Are you yet again arguing solely from the perspective of PC gaming? IGP was created initially for mobile and is thrown onto desktop SKUs as a free bonus. But the design intent was never for desktop. It was not solely for gaming. It was always for superior battery life and performance per watt for mobile products.
And if you look at the vast majority of ultrabooks, most of them are using intel HD graphics. Nearly all of them are. And these products, you gotta be kidding yourself if you think every student and every corporate worker that buys an ultrabooks want to game. Most of them don't game.
You must keep in mind that most people are not gamers. If I had a dollar for every time some ridiculous argument aumomatically gets thrown into a "gaming" mindset, i'd be a millionaire....that isn't the sole design intent of IGP. Intel created the iGPU at Apple's beckoning initially and gaming obviously isn't the strong suit of the macbooks. That said, intel has gained an incredible amount of performance with Iris Pro even WITH gaming. The MOBILE IRIS PRO has great performance in games considering the die size investment and has very very good performance per watt.
That is ultimately what IGP is all about. MOBILE. Stop thinking in terms of desktop. If you want desktop graphics, get real man. You should just get a dGPU and be done with it. If you want 4k gaming, on a desktop, you get a dGPU.
This is not the original design intent of IGP and never was. HOWEVER, with that being said, intel has made incredible strides here even with gaming performance. No, you can't run 1080p ultra. 1366x768 with decent detail gaming? Yes, doable with Iris Pro. 30 fps low detail 1080p with Iris Pro? Yes, possible. The mobile core with Iris Pro is actually trading blows with AMD's desktop LGA in graphics performance. Which is funny when you think about it, because the 48xx MQ with Iris Pro is mobile while AMD's 7850k is a desktop part. A mobile part trading with a desktop part. You tell me if that should happen.
While the Iris Pro mobile also has (obviously) superior performance per watt. That gap will only widen in the future while AMD is making baby steps in graphics APU performance. And that will put AMD further and further behind in the mobile market. AMD's prospects for mobile, basically, suck. Sorry, but that's just the truth. OEMS want balanced performance and intel overall is just better for mobile in terms of balanced products. And no, 100% of buyers are NOT gamers. Despite that, Intel's gaming performance has just gone way up with Iris Pro. I see a day when high end iGPU actually intersect with low end mobile dGPU. 10 years ago every notebook had a mobile dGPU. Now? Nearly all of them don't.