That's changing in Skylake according to the Anandtech article, so it should be four generations.
It was inevitable, although they seem to be doing it to an extreme form nowadays. That is, segmentation.
If you are talking from an enthusiast point of view, then it doesn't make a big difference. It's a lockdown anyway.
Intel knows their chips, unfortunately they are using that knowledge to the worst possible.
He said that the top-level graphics processors integrated in Intel’s chips, called Iris and Iris Pro, can outperform 80 percent of discrete graphics chips.However he thinks that Intel has done quite a poor job of communicating the benefits of integrated graphics.
Its in practice nonexistent.
If they want VOLUME, they should have put a GT4e in a Core i3 6100 and price it cheaper than the discrete graphics variant. $219 should do it. You save money. Yes the drivers are shoddy and they treat it as HD Audio, bland and uninteresting for gaming but people will get it for perf/$.
You advance technology by *pushing* boundaries, not making new tech ever higher in price. $2000 for a iGPU part(I am looking at you SP4!) is ridiculous. We should have seen a laptop where a Core i5 6200U device say costs $500, and a Core i7 6560U would be $650. People would get it, heck yeah.*
Or a $999 Core i5 Ultrabook with $1199 Core i7 Iris 540 option. There's only a $110 price difference between a Core i5 6200U and Core i7 6560U according to the official pricing page. If the company gets it cheaper from Intel and marks it up to sell it to you and make money, the pricing difference should roughly reflect what ARK says.
*But nooo, the manufacturers and Intel use a clever trick where you put the Iris parts ONLY in an expensive device. It seems there's an unspoken rule you can't use top tier SKU on a cheaper device. If you can't use a still crappy(but better) GPU at a cheap laptop that's more in fitting with the performance, what's the point?