But the FIA don't want to have cars on track that 'don't count'. They would have no interest at all in having 1/3rd of the grid effectively invisible to the championship(s). The only reason to have non scoring cars is because a) they don't comply with the rules (like Le Mans Garage 56), b) they are a visitor to the championship for a single round, or c) there is a constructors championship but not all teams in it have the same number of cars, and they need to keep it fair.
There won't be non scoring cars unless there's a solid reason why they should be. Forcing teams to run 'development' drivers is flawed too. Ignoring how you define 'development' (de la Rossa managed to qualify to drive in the Young Drivers Test recently), it would meean there are only 14 or 16 'proper' places in F1, and 7 or 8 mandated road blocks.
Either way though, there isn't gaps in the points for non scoring drivers. At least for the WCC. A secondary set of results is compiled and the points allocated against that, much like the BTCC handle the independent drivers and teams championships alongside the overall teams and drivers championships.
On another note though, I wonder if they would get an additional pit box? Would be a squeeze to go from 11 to 16 boxes at a lot of tracks, but 1 box is going to be a challenge if a SC comes out?