I think elemental would be fine if we could use the things we already have more easily BUT since its a new expansion we're writing about, I would like if Thunderstorm caused us to be untargetable for 3 secs after we use it. Part of the draw back of the current TS is that its easy for melee to get right back on top of us after we've used it. So the idea would be we TS and since they can't target us they can't charge, shadowstep, etc. Not gonna help as much if we're stunned but if we're not we have 3 secs to hump the closest pillar and/or heal.4) An escape move for elemental and an gap closer for enhance. For elemental it'd be cool if they could have something along the lines of blink, a hunter's disengage warlock's teleport or something like that => getting out of trouble fast and reliably. As for enhance, I could picture either an instant gap closer (we could get our wolve's leap) or an freedom effect added UF:FB (though baseline would be nice).
A possibility to get both things in one ability would be an ele/enh only ability along the lines of a warrior's jump. Ele could use it to leap into safety, an enh could chase enemies with it. Since you wouldn't need a target for it, you could also use it to gap close towards enemies behind pillars.
I think you'd be much more likely to get either a gap closer or a freedom effect but not both. Which you said already but I'd strike out the "possibility to get both things in one ability." I think it may be too much to have both, it'd probably be tied up in talents so that you'd have to choose one or the other. I'm thinking of all the uptime enhance would have. I believe we already have 2 ranged snares in frost shock and unleash frost baseline; or we can have ranged snares plus ranged roots depending on talents. So when you combine both a gap closer and a freedom effect with the snares and roots plus ghostwolf plus the glyph of ghostwolf and movement speed increase through unleashed fury frostbrand, I think that's most likely too strong. It seems very cata sub rogue-ish to me which I have to think there's a reason they changed them in MoP so that they wouldn't have easy access to all that stuff. I don't think windwalk being put on that tier was arbitrary, I think they don't want us to have freedom and an instant ranged root at the same time. So I don't think you'd be able to get a gap closer on top of it. The closest spec to that right now I think, not sure, is feral in 5.2 with the mass entanglement change but they're still restricted to a ranged root or a ranged snare, as far as I know. Doesn't make much of a difference given all the tools they have but its still not a point in enhancement's favor.
As for hex, I tend to think its fine the way it is because I think of the negatives that would happen if they changed it to be more like polymorph for elemental. It's likely it would become magic instead of a curse. Even if thats not a big deal to some players, it would probably break immediately on damage, and so now we'd have a glyph of hex that removes damage over time effects from targets. That's a major glyph and something I'd rather not see. I can't imagine that they'd have it be magic for elemental and leave it a curse for enhancement. So now enhancement has what its always wanted in an instant hex...except now its magic, breaks on damage, and they need a major glyph so that it doesn't. So if they changed it, I think its unlikely they make it a full polymorph. I could see it being a full loss of control but not spammable or not much lower cd than now. OR I could see them lowering the cd to maybe 30 secs but not being a full loss of control. Pretty much not spammable in either scenario. All of that is simply because its a curse and I don't think there's any way they keep it a curse if they make those changes.8) Hex: Change it so that in pvp as well, it will cause the target to hop around like it already does in pve. Furthermore, it'll become instant for enhance (so that we can use MSW more freely in pvp) and have it's cooldown removed/lowered to a very short time for elemental.
Capacitor is tricky, I feel, because of resto. Although I really really like the idea of making it invisible and triggering when players walk into it, again there's resto.7) Capacitor changes the way it functions. It could work either like Shadowfury (either exactly the same, or higher cooldown/higher duration), being instant and throwable baseline. OR, make it like a hunter's trap (invisible, and when you walk into it, it triggers) or maybe like a moonkin's mushrooms (remote controlled aoe stun mine)
Or, if all of that would be to much; change it to a HoJ clone. I prefer a reliable single target stun over a bad aoe one