i find 21's two yr experience in mining very encouraging/exciting in anticipation of their ability to roll out relevant IOT asic chips, esp for smartphones. that should drive things like batshit:
http://i.imgur.com/keXaz8c.png21's mining use case shows that blocksize has no impact to miners at all.
It shows that it has no impact on contractors who provide hashing to pools (the latter being the actual miners -- in most cases, there being exceptions such as the rare solo miner or p2pool participants).
