If you haven't checked the PTR notes regarding Arcane, it looks like it'll be pretty dominant in PvP. Biggest changes and combinations:
Ice Barrier replaced with Prismatic Barrier - same absorption but reduces magic damage taken by 15% AND reduces duration of magical effects (AKA: Dots, poly, and fear) by 25%
Paired with Mage Armor (which should be additive reduction in this case) giving you 50% magic duration reduction. 8 second poly turns into 4. Pick up Relentless for another 20% reduction and poly now lasts 2.4 (70% reduction in total) seconds. I could be wrong, but I was pretty sure duration reductions are added together instead of multiplied. If it's multiplied it's a 55% reduction which is still great.
Prismatic Barrier has a 30 second cooldown. With Mana Shield (new talent) it doesn't have a cooldown meaning you can spam it nonstop at the cost of having 20% of the damage drain your mana. If you're getting tunneled into the ground, you can spam this almost non-stop for several minutes.
Overpowered was dramatically changed and buffed - now it grants 70% increased damage and an additional 70% mana cost reduction. With the increase in mana cost on Arcane Blast, this will offset the total mana spent pretty significantly. Within a burst window, you can easily spam 500k hit ABs. With Unstable Magic you'll get another 250k on proc.
Time Anomaly went from a shitty 5% proc to a massive 50% proc. Partnered with Overpowered, you have considerably more uptime to do damage now.
Pretty sure this is going to make Arcane incredibly viable, if not the dominant spec.