First, we all know that cryptographers are not any good at the maths so they will be particularly mind twisted.
Second, Bitcoin is inflationary, not deflationary, as you have asserted. Inflation is the increase in the currency supply. For the next few decades, there will always be a constant increase in the supply of bitcoins created. The block reward changing will merely decrease the rate of increase but the rate of change will still be positive and therefore inflation of bitcoins will still be happening.
Third, with regards to miner's income just look at the performance of the GIGAMINING or BITBOND assets. On 7 May 2012 GIGAMINING produced 0.02333570 BTC per bond or about $0.122512425. On 27 Aug 2012 it will produce approximately 0.01731418 BTC per bond (~75%) about $0.174474055 (~142%). The differences are due to changes in difficulty and exchange rate.