All that said, ya - without seeing what the full potential of all of the above is yet - I very much suspect this is going to get nerfed. Then again, it's all based on a trinket - a trinket which is probably almost as overpowered for Destro Locks and Fire Mages - so the most logical nerf would be to just nerf the trinket, rather than to presume we are all managing to line up 100% crit for 4 seconds with 30% haste for 10 seconds procs, and re-apply out dots for the rest of the fight during that small window (and, have that small window randomly occur near the start of the fight).
Since it's all predicated on synergies between stacking proc effects they are adding - it could go live (probably through negligence, or the risk of it occuring is so small they don't consider it an issue). If it does go live, it could have adverse effects for Shadow actually - since the randomness of our DPS would suddenly be colossal (if all this lines up on the pull, then that Spriests parse is going to be hilarious).
The top end parses on Raidbots (which players often point to as a measure of balance) could show Shadow as being the 'best spec', but in reality, it would be because of a huge delta from top end parses to average: based on who has all the right items to pull it off, has BiS gear, thoroughly knows Shadow and how to exploit this, and then has crazy luck in lining it up on the pull.