There are a couple of ways in which the amount of Steem in the reward pool could be increased:
* A Hardfork change: For example an increase to the inflation rate which would increase the amount flowing into the reward pool.
* A blockchain outage: After HF20 pretty much all users stopped voting for 5 days. This increased the reward pool substantially as Steem was not being claimed from the pool.
However neither of these changes would be beneficial to the Steem economy.
The best way for the amount of rewards to increase is for the value of Steem to rise so that the Steem coming out of the reward pool is worth more, even if the amount of Steem in the reward pool is unchanged. This is something we all need to work towards together.
Say pretty please to Ned and top Witnesses.
There's no need to increase the supply of Steem at this time.