We've been given the first concrete information about
how the new gear stats will work in the expansion, Cataclysm. As you'd expect from something with such a name, it's going to be a bit of a shakeup.
The plan is for these changes to come into effect before the expansion is released, probably alongside wholesale talent revamps, so we have the joy of logging in one day in the not-too-distant future to see our gear reworked and our talents completely overhauled :)
It's much too early to worry about what this might mean for shadow priests. At this stage, in fact, very little would appear to be changing. Spellpower will vanish from our gear, while intellect and stamina will increase. Intellect will provide spellpower indirectly, so that we won't miss the lack of spellpower numbers on the gear. Hit, crit and haste will stay the same, and continue to function in the way you're used to. And spirit will probably vanish from most of our items.
The changes to spirit may be a cause for intrigue. This stat will no longer provide any benefit to caster dps. So we can expect talents such as twisted faith to disappear, as well as our mainstay glyph of shadow. We are promised mana regeneration in other ways — perhaps through buffs to dispersion and shadowfiend (although how shades are expected to level to the point where they can get them is another matter; this, we are told, will change too).
Divine spirit will go too, I assume, as we are told there will be no raid buffs for spirit in the new world order. To be honest, divine spirit was never the best buff in the world, but I like it. I like the shiny-blue-man icon, I like the connection it gives priests to spirit (their most idiosyncratic stat), and I like the fact that it's something melee don't want (I'm so sick of those DK buffs clogging my screen and making my hands glow). So I will mourn divine spirit and remember it fondly.
The spirit changes could actually cause many dual-specced priests a problem: we might be left with some big holes in our off-spec gear if we're not careful. It really depends on how Blizzard decides what gear currently constitutes "dps", how they convert that gear, and how they rework mana regeneration for healers. There is a chance discipline priests will need spirit as much as holy priests, so all those months of stocking dps cloth could leave us with a bit of a headache. We'll have to wait and see how this one plays out.
In the longer term, this change to spirit might go someway to restoring the once-rigid dividing line between healing and dps gear, and reduce the competition on healing priests for gear.
The introduction of a new "mastery" stat on items should also dissuade leather, mail and plate-wearing casters from rolling on cloth, because the intention is for this stat (function still a little vague at this time) to only apply to that item's primary class types (e.g. druids for leather, shaman for mail etc).
Things are starting to look interesting again. I can't wait for the bun-fight on talents to begin.