You really love the GM comparison. Okay, let's play
First off, McAfee was not $7.68 billion down the drain (though it was a boneheaded and utterly stupid acquisition). The division was actually modestly profitable for quite a while, and Intel ended up selling a big chunk of it, getting a partial refund (while maintaining a 49% stake which it can further monetize if it wants to).
I wish you would cite your sources. IoT business for Intel generated $2.6 billion in revenue last year (larger than AMD's entire x86 CPU business, FYI) and it generated $585 million in profit.
And I don't think expensive Xeon/Xeon Phi chips sold into self-driving cars in the future will be "low margin" or "tiny"
x86 is not a disadvantage here, and cutting edge mfg processes will be valuable in the more performance sensitive markets (i.e. self driving cars).
It's true that they're out, but this little startup in Cupertino, California thinks its modems are good enough to use in the iPhone 7 and they will likely be used in at least two more generations of iPhones. Intel has decent (and improving) cellular modem technology and it's already generating them hundreds of millions of dollars per quarter.
Intel already dominates the market for machine learning/deep learning with Xeon and they're pretty much throwing every asset they have at it going forward:
NVIDIA is awesome and builds really great stuff, but the "CUDA lock in" that you cite -- which is definitely a headache for AMD -- has an effective counter in the form of, "oh you're building your software to take advantage of those shiny AVX-512 units on our Xeon E5 processors anyway? Well, good thing this Xeon Phi is software compatible!"
They make big profits in server CPUs, but PC processors actually generate far more revenue and total overall profit dollars than server CPUs do.
Anyway, profit margins don't "subsidize" other lines of businesses for Intel, not really. Of Intel's major business units (Client, Data Center, Altera, IoT, and memory), only one is not profitable -- memory. The rest are all immensely profitable, which means that not only do they generate enough gross profit to cover R&D, but they generate far in excess of what Intel invests -- that's profit.
Cutting margins means that Intel's profits will be lower (which is a problem), but there is a long way between "oh crap, can't fund future R&D" and "oh, we reported less profit than we did last year and investors are not happy."
It's a good thing Intel develops really good products.
If I win the lottery tomorrow, I'll be a multi-millionaire.