Dedicating mining processors are (slowly) hiting the market.  They are significantly more efficient at mining and will drive difficulty up by 20x (and probably more).  Expect your mining revenue per MH/s to decline by 95% or more.  Buying new GPUs today for mining is a good way of piling lots of cash up and lighting it on fire.

As for your general questions.  The 21M coins won't be mined until the year 2140.  As the amount of the block subsidy declines (block subsidy is halved every 210,000 block ~4 years) it is expected fees will increase to provide the revenue to secure the network.  Fee have already increased from ~0% to ~2% of total miner revenue.