You could still KYC and play with both, you just couldn't enter the same tournament with both. It would be using the same KYC system Splinterlands already uses for purchasing credits.
For the record this was not my suggestion, but it's been brought up a lot, so we're going to have a vote. I don't know if this will even make it to a full proposal.
RE: SPS Governance Proposal - Require KYC for DAO Sponsored Tournaments