What ideas for preventing Ethereum PoS stake concentration do you think are the most promising?

CEO @GridPlus 

Hardware signing security focused on smart contract chains and account abstraction wallets.

I'm not sure. My impression is that despite the attention this problem receives, it remains under-studied and under-resourced relative to its importance. I know many people are shifting attention towards it.

I do think the social-layer will play an important role here, and people are wrong to dismiss that approach.