From my point of view, Steem is a currency, convertible in a backup of value (SP). I am pretty sure that a market will develop from Steemit and that much people will start using Steem as measure of value of the goods and services they will exchange.
The fact that the Steem amount will be increasing won't lead to an increase of prices until it has reached all its potential users.
For example if you make a clone of the USA, doubling everything, you would need also to double the monetary base. This is why circulating Steems are designed to increase: because the users increase. We have to pass from some thousand users to a couple billions :)
Once Steem will be diffused all over the world, we'll have a fantastic tool to establish all togheter which changes will be needed in the Steem monetary policy.