Oh boy... The Halo is a doomed fix. Its a small plaster on a shark bite... There are some major flaws such as the gaps between the middle stem can still allow debris, springs, bolts and other car stuff through to the drivers head that could cause injury. Not to mention the visibility could be a factor at places with large elevation change such as Eau Rouge. (But Rosberg already tried it at Spa and reported not much difference).
Plus I wonder how this device will effect the aero flow over the car, it can create an unstable vortex just before the rear wing which could mean downforce being unloaded in conditions of changing direction quickly. Suzuka esses for example.
In my opinion they SHOULD have spent at least 5 years developing this technology to make sure the final design was a fault proof idea. The Halo has a lot of things wrong with it. So too the Aeroscreen and the Shield. This is why we should have had a lot of time dedicated to finding a solution.