I think for you (as it will be for most people and orgs) there has to be some catalytic event. As an individual, that is usually related to failing hardware, as an organization - usually related to server/data center upgrades or specific "must have" applications that are not available on the old OS.
If neither has a change now event, then the change is likely to happen slowly and this is where MS is needing to get into the high change markets of phone and tablet. If they can convince users that their experience is good, then when they are looking around for new tech MS may be on their list of potentials. FOr the business user, this will apply pressure through consumerization to force a more rapid change than can be expected from standard roll over cycles.
Either way, it either has the draw card for you, or not.
For me the big draw is that the Surface Pro appears to be both a laptop and a tablet at a respectable weight and size. That means I can avoid having yet another device and can in fact streamline my life. I consider that a significant pull and will head that way as soon as I can.
As for users, again, I think any change can be handled cleverly but as you rightly say, if there is no need to change, why bother? I agree with this sentiment.
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