When bitcoin hits mainstream, the block reward will be small and mining profit comes from transaction fees. Transaction fees are partially based on size already, and in the future I believe that it will increasingly depend on size.
I would love to know the percentage of people involved in BTC that are not:
A) Miners
B) Speculators
What do we think the percentage of people using BTC are actually 'using' BTC.
That's something that I'd be interested to know too. Right now, it looks like a lot of interest in Bitcoin is there purely for mining and speculation.