No concrete details of the airdrop have been decided yet – and they won’t be until we’re confident that we have a mechanism which the Zcash community considers to be secure, privacy-preserving, and fair – and which could also be reused by other parties (to conduct other shielded airdrops) in the future. That’s our first priority.
Right now, we’re looking for technical feedback on this proposal (from technical folks in the Zcash ecosystem). I’ve reached out to a few folks at ECC but haven’t heard back yet – any help appreciated!