According to Foresight News, Ava Labs engineering lead Patrick O'Grady has proposed an upgrade for Avalanche subnets called Astra on GitHub. The upgrade aims to introduce a new type of staker, known as Subnet-Only Validators (SOV), who can validate Avalanche subnets and participate in Avalanche Warp Messaging (AWM) without having to synchronize or become a mainnet validator. The proposal requires SOVs to pay a refundable fee of 500 AVAX on the P-chain to register as a subnet validator, instead of staking at least 2,000 AVAX. The proposal intends to transition to a 'pay-as-you-go' subnet validation and enhance subnet security with AVAX.