That is my understanding. You get more SP over time to offset inflation, but that inflation also drives the price down (more supply = lower prices). Without new demand, I'd expect these to offset each other for the most part.
That means the only way to gain here is to curate or post (grow your SP above the inflation rate) or hope demand increases and drives the price of SP up so the SP you have gains in value.
RE: VESTS - the true power of steem and why I personally put 100 BTC into steemit ecosystem