RT has desktop mode.
It's patently untrue that the web is the future for "the kinds of apps that made windows dominant"
Actually, windows was dominant for every kind of app. The growth in apps of all sectors - LOB, entertainment, etc -- is on devices, and people regularly pan device apps that are just thin shells around a browser control.
People want native apps on their devices. MDD (multi-device-development) is something enterprise is very interested in -- they need to deal with a BYOD workforce, and they always want to economize on IT spend.
If it had been feasible to make Win32 apps run well on ARM, don't you think we would have done that?
The most insightful thing you wrote is this:
"But yes, Intel hasn't been asleep, and ARM is no longer as much of a requirement for mobile devices"
Consider the following -- and note that while I work at MS, I am neither privy to, nor attempting to disclose -- any high level strategy
1) Microsoft delivers a lot of value to enterprise customers because of app compat
2) think back a few years at what the CPU landscape looked like -- think about the power consumption of Intel's offerings. Remember, there was no ATOM yet.
3) app compat, battery life, performance -- if you don't have a low-power native x86 processor, you can only get two of these at a time.
4) Enterprise customers want all three
5) Intel, years ago, didn't appear to have any intention to deliver a low-cost, low power x86 part
6) this meant that MS would be unable to deliver low cost, new form factor mobile devices that could still run legacy software
7) this would force a wedge between new form factors and the Microsoft platform advantages (great compatability)
Clearly, what needed to happen is that something had to convince intel to develop a low cost, low power, good performing x86 chip
Based on 20+ years history, considering ARM, AMD, dec Alpha, etc, what makes intel innovate well and do its best work?
A credible marketplace threat to Wintel.
Claim: The purpose of Windows+ARM was to force intel to develop a low-power, low-cost x86 chip. If Windows+ARM took off in its own right, great. But the main purpose has been to secure a $99 x86 windows tablet -- which means that enterprises have the price points and form factors they want, and the app compat they need.
I happen to like my RT tablet -- but the Surface Pro is a credible do-it-all device, and now software that runs on the Pro is the same software that runs on your $99 HP tablet and your $4999 gaming rig.
Back when windows+ARM started, the intel hardware to allow that continuum didn't exist.
As I said -- nobody at MS tells me how things really go down. But this is a high stakes game. The people at MS aren't stupid.