Steem is growing. The market cap last January has reached already 2 billion USD, so 1 Steem was worth 8 USD.
If Steem keep growing, the chance is big, during the next bull run Steem market cap will reach the 10 billion USD, that means 1 Steem will worth about +/-40 USD. That could be even within 2 years, but let say after 5 years, if we don't want to be too optimistic! :)