[Asus  Eee Pad Transformer Prime] e.mote:
>Except Office isn't a Metro app, even on WINRT.

>Having played with Metro on Win8, I can see Metro working well for tablets, but never for full blown Windows productivity apps like Office.

I agree that certain categories of applications are so ingrained with the WIMP (windows/icons/menus/pointer) paradigm that re-architecting them to a touch-based UI would amount to a grounds-up rewrite--much more difficult than the already difficult task of architecting a new touch UI.

Office is an agglomeration of code, accreted over its long life, that had grown to be an uncontrollable mass. MS tried to simplify the UI in recent versions with the ribbon bar, but with limited success. The problem was that users had already learned Office's old entangled UI, and any UI change would necessitate another (high) learning curve.

That's the balancing act. Even if the re-write were successful and we have a wholly Metro-based Office, that's probably not what we want, because we'd have to learn Office anew. Office is MS' largest cash cow, and forcing its users to re-learn its UI from scratch would lose much of the userbase. That would amount to product suicide.

For better or worse, Office would need to stay pretty much as it is, not only because of the technical aspect, but also be human (learning) aspect, and the business aspect of keeping your userbase happy. Any change must be gradual, and switching wholesale from WIMP to touch is not gradual.

Putting Office aside for the nonce, let's consider the question of whether a touch-based UI can replace WIMP for all uses including productivity.

First, no doubt there is an entire industry of ISVs who are burning the midnight oil to solve this issue. This is as big a change as from the CLI to the GUI (WIMP), and I doubt there'll be a perfect solution out of the gate. More likely there'll be a hacked-together solution--like the present form of Metro/desktop integration--that'll be refined over time. We're all beta testers.

Let's examine the fundamental difference. We can say that touch controls are more imprecise than mouse controls, not because our finger is larger than the mouse pointer, but because the use of the screen for both input and output exacts an inefficiency: When we touch the screen to make an input, that portion of the screen being touched can't be used for output (can't be seen). This is the major inefficiency of the current direct-touch paradigm.

How to improve upon this? It's straightforward: Instead of direct-touch, employ indirect-touch. (Recall that the mouse is an indirect pointing device.) Don't use a single screen for both input and output; use two. Have a smaller screen dedicated to input, ergo replace the keyboard with a screen. BTW, this also solves the ergonomic issue of needing to raise your arms to touch the screen, as will happen with the current generation of Win8 touch laptops.

This has been tried at various times before, but all failed because they lacked the necessary OS and application support. But there's inkling of a comeback, eg Microsoft's recently-announced SmartGlass, which uses an existing device as input for its Xbox360.

Another issue is that two displays eat more power, which is a problem for mobile. One possible solution is to use a low-power panel (PixelQi? e-ink?) for the input display.

There are yet more issues, such as lack of tactile feedback for fast keyboarding on a screen. Recent advances in haptic feedback (Engadget link) look promising for this.

This issue obviously is much more involved. Suffice it to say that, yes, productivity apps are possible on a touch-based UI. The gist of the above is to show that it won't be an evolution of just the OS and software, but the hardware side will need to evolve as well.