Valve is a privately held company, so it's under no obligation to share financial details with the public. As a result, we don't have a perfectly clear picture of just how much of the PC gaming market has been gobbled up by Steam—or downloadable games in general. The market for digitally acquired titles is certainly growing, though. EA's digital revenue was up 55% last quarter. For the current fiscal year, EA expects downloads to make up 40% of its projected $4.3 billion revenue.
In an interview with Reuters, COO Peter Moore says EA isn't far away from shipping more downloadable games than retail-boxed copies. The firm's digital sales could outstrip those of physical copies in a few years.
The market as a whole may be at parity already. Reuters cites an NPD Group report claiming that sales of boxed games dropped 20% in July and now make up half of the overall market. Perhaps last month's Steam summer sale was partly responsible for the sharp decrease in physical sales. I'd be curious to see how NPD's numbers look after the flurry of new releases expected during this year's holiday season.
Downloadable titles seem to be particularly popular in North America, where Steam has long had a foothold. Square Enix's upcoming open-world action game Sleeping Dogs, for instance, won't be sold in a retail box at all in the U.S. and Canada. EA has no plans to phase out packaged products just yet, though. As long as there are consumers who want physical copies, Moore says EA will provide them. However, I suspect those retail-boxed games to still be tied to EA's Origin online service.