According to a Medium post

According to a Medium post, eligible holders of LUNC (Luna Classic), USTC (UST Classic), and aUST – will receive the LUNA airdrop on the new chain upon genesis.

Terra Luna 2.0 Airdrop – Answers to Most Common Questions

All You Need To Know About Terra 2.0 and the LUNA

Terra 2.0LUNA Airdrop - Medium

Terra 2.0 Reveals LUNA Airdrop and Launch Date

Terra Chain 2.0 and LUNA Airdrop Approved for May

LUNA 2.0 listing and Terra airdrop distribution schedule