Maybe an obvious point, but the successful hashers (successful grinders) can create multiple coinbase outputs to use multiple hubs, reducing the liquidity requirement of each hub.

An example of coinbase transactions paying to three hubs instead of one:


Using N coinbase outputs reduces the liquidity requirements of a hub by a factor of 1/N.

So if you chose N = 5, today's block reward of around 12.5 btc means each hub only needs to provide liquidity for a reward of 2.5 btc.

Each output only costs about 20 more bytes to create (and about the same to spend because of the segwit discount).

This is an easy way to have many more people being able to run these p2pool hubs. Because of pareto's principle, reducing requirements by 1/N means the number of additional people who own that many bitcoins is much more than a factor of N. (Note that hubs need to own around 50 times the block reward, so more than just 2.5 btc)