I think it would be cool if there were an airdrop to other alts to spark interest (one time)
Maybe Bitshares, LSK, other ones with public chains.
I disagree. There has been plenty of time to get onboard and I totally feel now it's the right time to reward Byteball users/merchants/holders only. I don't see good reasons to implement what you suggest.
We need more trading volume for Byteball only to attract new speculators (yes, they are good tools to get a coin reach its potential).
my two cents though