yes its viable, and might pwn face. EJ via ptr says nice things about it. it has a benefit of double dipping +hit so you get 6% hit (from talents) to arcane spells. (elemental prescision to prescision)
hit cap (with full raid buffs)- 8% (7% with drainei) 210 hit raiting (184)
yellow- spellpower and int
blue- spellpower and spirit
glyph of arcane blast
glyph of mage armor
glyph of arcane power
AB AB AB AM-ABr (cast arcane barrage as soon as the fifth arcane missile is released, before it lands) repeat. you will want to pop all your cooldowns at the fights opening, unless you are saving it for a sarth + fight or something like that
torment of the weak helps it out, making it on par with ffb (depending on itemization better)
(this is the build i would run, not the typical 18/53 you find on EJ spirit is not worthless in this build btw)
i inclue 20% mana regen while casting over 4% more crit on pyro because in 3.0.8 we will have less mana regen from paladins, and fire is significantly more mana intensive than ffb.
itemization (after hit cap)
hit cap- 14% - 368 hit rating (341 w/drainei)
yellow- spellpower and crit
blue- spellpower and spirit
glyph of imp scorch
glyph of fireball
glyph of molten armor
unchanged (spirit is still 100% useless)
the weakest build. (still fun though) and very very mana efficient. spirit is 100% useless (it makes me angry that there is so much spirit gear, and we have to go into the 4th tier of arcane to get spirit regen while casting)
hit cap- 11% 289 hit rating (264 w/drainei)
glyph of frostbolt
glyph of molten armor (glyph of fireball, glyph of ice lance may be on par)
glyph of water elemental
the theorycrafting numbers put arcane (i believe the rotation is AB AB AB Abarrage/AM(if missile barrage procs)) ahead of FFB and deep fire, just slightly behind (if i was reading EJ right). FFB and deep fire are neck and neck, some people have FFB ahead, others have deep fire, it depends on gear and itemization. the more crit you have, the better FFB is. both builds value crit (crit>haste... always (for fire builds)) but haste is closer to crit for deep fire, which may be a better option with gear choices available (they like to give haste to casters, because most casters get more out of haste than crit).
arcane finally is a tree that doen't need a filler spell. it also isn't spamming AB until you need to frostbolt for mana regen. i like what they've finally done to the tree.
they fixed torment of the weak. bout time. too bad we can't get torment of the weak into a proper frostfire build. that would be too op though.
deep fire requires 3% more hit, cuz you don't get any from talents. arcane requires 3% less hit, because you get 6% with talents. arcane should be easier to impliment in raid, because your not monitoring living bomb, and you cast your proc'd spell at more controllable intervals (it doesn't have a time limit)
frost needs loving still (or blizzard thinks that 3 good raiding builds are enough, which is more than can be said about any other pure dps class, and only 3 other classes period (droods, priets, pallies)