So on the 11th medal, the following is how it works:

1) IOC Program Commission make recommendations on number of medals. There are planned deletions of medals for multiple sports, so it is not just an issue for sailing
2) IOC Executive Board meets on Dec 10-12(ish) and everyone is hopeful that they will then make a decision, but it may not be made until a later meeting
3) ISAF then have to decide what discipline to award the 11th medal - it is not automatically the multihull.
4) ISAF then need to decide what class to choose.

The decisions on points 3) & 4) will not be made until the May meeting at the earliest. Given that this means that it will be only a bit over 3 years till the Olympics, it is unlikely that ISAF would risk a new boat, and the Tornado would be most likely to be selected.