A miner can put as many transactions as they like in a block with no fees.
This is solved by implementing IBLT as the standard block transmission method, although this is not a short-term goal.
A miner can get his or her IBLT blocks accepted only if the vast majority of the transactions in it are already known to,
and accepted as sensible, by the majority of the network. It shifts the pendulum of power back towards all the non-mining nodes, because miners must treat the consensus tx mempool as work they are obliged to do. It also allows for huge efficiency gains, shifting the bottleneck from bandwidth to disk storage, RAM and cpu (which already have a much greater capacity). In theory, 100MB blocks which get written to the blockchain can be sent using only 1 or 2MB blocks on the network. I don't think many people appreciate how fantastic this idea is.
The debate here is largely being conducted on the basis that the existing block transmission method is going to remain unimproved. This is not the case, and a different efficiency method, tx hashes in relayed blocks, is already live.
Okey dokey. My latest straw-man proposal is 40% per year growth for 20 years. That seems like a reasonable compromise based on current conditions and trends.
Gavin, I hope you proceed with what you think is best.