Only a looming governance problem, but not in any way a financial performance problem. Only the latter will trigger any real reaction from the markets, and Bogle thinks that won't likely happen until 70% of market under passive indexing at a minimum.

Governance concerns are not structural and addressable when it reaches a critical mass. I wouldn't be overly concerned, just put in a word when someone starts to lobby for regulation requiring delegating voting power back to index investors, and fund managers having to vote the preponderance of pro-rata voted shares.