At some point there will be another layer to YC from successful exits in previous batches.

Already the number of partners is growing, and as more YC companies exit successfully you will probably see more of that, remembering your roots and who helped you up would be a powerful motivator into completing the cycle.

If YC can somehow manage to maintain communications through for instance multiple tiers with bypasses if needed it could get very big.

Every brushfire starts with a spark!