Buying a cpu today to upgrade a year or 2 later for something like hyperthreading and/or doubled cache is likely not worth the money spent (unless the price they charge is something very small, as in $20€) on the upgrade vs the performance increase, specially if the ram is holding back the upgrade the customer thinks will get.
Guess it depends. My laptop has 8Gb of ram. an OCZ Vertex 2 SSD and Win7 64; my laptop hits a CPU bottleneck just turning it on. If I had an i3-330m, I'd be waiting probably another fifteen seconds just to get my desktop. Since the initial price difference between an i3-330 and an i7-640 would be several hundred dollars, I don't expect it to necessarily be
cheaper to upgrade it after it leaves the factory. But I also don't expect it to cost more than the "bare" i7 processor would, either. And maybe I only 'need' an i5-520m's worth of performance out of it, or at least maybe the upgrade cost to that level of performance makes more sense... Dunno.
And for laptops that will just be good to help drain the battery life faster(also would the laptop be able to stably handle the extra TDP say during summer under heavy use? There would be a good chance to increase problems), unless its always plugged on.
Well, the i3-330m, the i5-520m, and the i7-640m are all 35W TDP processors. In fact, they're all the
exact same die with a bit of binning perhaps and some parts fused off and settings hard-wired. The i3-330m has no turboboost, no AES, 3mb of cache and runs at 2.13ghz. The i5-520m has 2/4 bins for turboboost, does have AES, 3mb of cache, and runs at 2.4ghz. The i7-640m has 3/5 bins for turboboost, does have AES, 4mb of cache, and runs at 2.8Ghz. But they're all the same die, and they all are 35W TDP parts that feature onboard video.
As for the rest? Who are you to say what is more interesting to the entire customer base of Intel's wide range of processors? I can imagine LOTS of sales for this sort of upgrade, which is what they're REALLY after.
It's not going to stop my personal upgrade path; I buy what I want and typically upgrade the entire machine when it's "slow". But my usage (and likely, your usage) is not the typical usage of the grand majority of PC users out there.