First off I would like to state that I am completely ignorant of the role and feel of shadow priests in PVE as of now. This post will cater to more PVP balance and the role shadow has in arenas.
With upcoming utility nerfs coming to shadow (Mass despell, Life swap) Previous nerfs to heals (Though I acknowledge they are needed across the board on all non-healer specs.) And the buff to Shadow damage, I fear shadow is falling out of their extremely niche, but necessary role in World of Warcraft PVP. I also fear Blizzard has a new vision of pvp becoming a mongoloiders dreams, in which training a healer is not a WAY to win, but HOW.
Shadow right now is set in the spot that feels like a very unique role in pvp right now. I like to call it, the "anti-mongoloid." But removal of Shadow utility may cause us to fall out of this position. Instead of removing this sort of game play from the game, I would recommend the growth across all specs and classes, the reason Shadow is one of the highest represented classes right now is because of their good damage, and amazing utility.
I know in most cases just because one thing is overpowered right now, doesn't mean that everything should become better, but rather the over powered thing become worse. I feel the direction wow pvp should be moving is towards the utility > damage method though. Right now burst feels too important, more important than landing good cc chains, and proper usage of defensive for yourself or team mates.
To get on with if shadow is in need of a rework or not , I feel they do. They seem to be pushing hard pvp nerfs onto shadow, but with no real effect. Rather than balancing Shadow, they are just getting dumbed down to lose their identity and unique utility they bring to pvp. If these massive utility nerfs do bring a balance to high rated representation, good I'm glad, but I am not glad to see my favorite spec lose its feel that I was so ecstatic to see it really thrive and grow with at the release of MoP. Would I be mad if other classes were given good utility as well as shadow? No! I'd embrace it, it would add much needed depth to the pvp scene.
Shadow right now is great, and I love the fact that we have a sense of being differentiated from other dot wizards in wow, but I fear that massive utility nerfs may cause Shadow to lose its unique role, and begin to feel like an identity-less wizard which could be any other dot class. Shadow may be in need of nerfs, but it may ruin the spec if whole, unique and useful spells are completely removed from arena play, and some become nearly useless in higher rating brackets. Shadow may be in need of a rework to allow them to thrive again, but in a more balanced manner. (And maybe a few more insta-casts please?)