Rotate PoW algos (including RandomX) depending on the hash of the frontier account-block for improved resilience. This would make a PoW lane spam attack from multiple account-chains very costly because with each transaction the attacker would need to switch between CPU, GPU or ASIC hardware.
Interesting suggestion. Perhaps we can work on this problem iteratively and harden PoW in the future. The additional complexity will delay dynamic plasma at this time.
I expect the initial feeless dynamic plasma implementation will be similar to this, though I still think we need account-level dynamic constraints and cooldowns.