just do the math
2 to 10th power is 1024
that is 10,000 users to 10 million users, in 10 years.
if steemit gets traction and can grow virally, then the problem would be that 10 million users is achieved far sooner than 10 years. In that case, we will see a proportionate price increase during the time it is ahead of the double per year pace, and then it will come back down to where it is now.

At least the fundamental value will do this, how the markets will react is a different issue.

Now keep in mind that having the price come back to 0.005 BTC in 10 years might sound like boring, but dont forget there is 1000x the STEEM. So with doubling every year, STEEM can maintain price, but the SP is what will store this compounding as the underlying vests stay much less changed.