AMD has had some pretty terrible drivers over the years. I was a victim of many of them. They're better on average now, but their history isn't preventing current sales. I'm not sure we can really know what Intel is going to produce. I wouldn't use their IGP as a baseline as I doubt they were really trying there. No one was buying their CPU's because they wanted to game on the IGP so there was no revenue incentive in it for them. I'm not expecting much from their driver team at launch, but given current market conditions the drivers just need to be good enough to make cards a viable option.
HPC is why Intel is doing all of this. No arguement there. If they are highly successful there, will they bail on gaming? Or if they fail to make inroads in HPC, will they abandon all GPU development? Intel is not afraid of bailing on market segments no matter how much money they dumped into R&D.