I think they have to verify the names of those who voted against membership lists in each country. That process I'm sure will take several weeks. And even if it passes, it sounds like the ISAF has veto power and will use it.
Is it really true that ISAF has said they will refuse to approve the fundamental rule change? The source of this assumption seems to be this Sail-World article which said
As recent written advice from ISAF to the ILCA had according to informed sources, already rejected the proposed rule changes, the confirmation that Kirby is now seeking to bring the parties together, will it seems remove any argument that the ILCA has a role to play in this matter.
I'd be very surprised if that were true - a decision like that could only be made by one of the millions of ISAF committees and their meeting minutes are all in the public domain. They may have requested further info, or expressed concern at the whole situation, but that would be about the limit of it.
What ISAF have pointed out (as Tracy mentioned in his summary of Heini's talk at the SF Worlds) is that they didn't approve Kirby's sale of the design rights to GS in the first place, and weren't even told about the sale at the time. This is probably what has led to GS returning the rights to Kirby.