I am trying to think about it in regards to market cap. Right now we're at about $20M. However in a year its been stated that there will be 500M steem in existence. If we maintained a price of about $1 per steem, we would have a $500M market cap. Thats definitely possible, and would make me a millionare, so its my preference. It might be a tad optimistic though.
I also think that it is critical to consider this from a market cap perspective.
See this article for more detail on how to properly calculate the market capitalization of steem.
Fixing that link for you https://steemit.com/steem/@dantheman/how-to-calculate-the-market-capitalization-of-steem