I did some minor mining calculations yesterday and the results should be communicated. At the current rate of difficulty increase we will see the difficulty double itself every couple months and eventually plateau once mining is no longer profitable. There is a very real possibility that we hit the ex profit zone in just four months.
The difficulty doubled from February 3rd to March 30th, effectively cutting mining yield (revenue) by half. However the price kept up with the hash rate increase and this resulted in an impact that only experienced miners really noticed. The difficulty then doubled again from March 30th to May 29th having a similar impact. Since May 30th the hash rate has increased by 30% and with ETH continuing its ascent in price per coin we can expect this trend to continue.
What this means for you - If the coin value doesn't keep up with the difficulty, expect major decreases in profitability. Realistically this is going to happen and it will happen this year. Another thing to consider is if you believe the coin value will keep up with difficulty then consider just buying the Eth outright and riding the curve. This method is significantly less risky and requires almost 0 level of effort. Alternatively, mining will still be a profitable business but require users to be more proactive in upgrading their rigs with new cards and selling their old cards for salvage value, or perhaps switching to a coin that is less difficult.
Just thought I would at my $0.02