3. Vertical scalability that reduces variance for all miners.

This is where the real challenges lie.

For p2pool to support large mining operations, and still be able to attract medium, small, and micro miners we need completely new share difficulty and payout structures.

The first step here has nothing to do with code, some completely new concepts need to be developed and generally accepted by p2pool miners. Once we have those concepts down, and can demonstrate them to be technically possible, we can seek out devs with the chops to pull it off.

This may seem like no big deal, but I assure you it is. Here is my first crack at it:

Payouts
While miners meeting a certain threshold could still be paid directly from the generation TX, smaller miners under the payout threshold when a block is found, lets say BTC0.01 to start, would be able to see their p2pool earnings down to the Satoshi in real time, but would not receive a payout until reaching the threshold.