WARNING: The following contains my own opinions
I can understand that PC gaming sales are going backwards.
Firstly, there are only a few gamers our there that are actually aware of Steam. i've met a lot of people that love playing games, own a PC and a console, but simply does not have, or never even heard of Steam. The fact of the matter is that broadband adoption in SA is still relatively low. I think this is the reason why our country has very low Steam action compared to console or physical copy sales. I am pretty sure that more than 60% of all PC game sales in SA are done over the counter, rather than over the internet. It's the reason why stores like BT Games, Look&Listen, Top CD and various others can still maintain, and grow, their gaming section.
We may not be buying physical copy of discs anymore, but we are really a small section of the greater gaming market in SA. I do not think we represent the bulk of the market. It is why physical sales will have a much bigger impact on overall market performance than online transactions.
I am reminded by a article MyG published with Steam statistics a while ago. It showed activity and number of players throughout the world, and I remember remarking just how low our activity stats are compared to the rest of the world.
Looking at the demography of our country, and taking into considerations various socio-economic factors, I think it makes sense that our country is showing a decline in PC sales revenue, as our market is much more indusive to console and casual gaming than PC gaming.
IMHO...