hmm, to be honest, for a game that you could just download, paying anything for it is fairly impressive, the key to its success is not its retail sales, but the playtime for it, and to be honest, while i was playing it for a review (uk release) the servers were always 90 or so percent full, the game is pretty packed, and its still going, so i dont think it is a failure, further it cannot be expected to break even on retail alone since it costs but 15 dollars new! and besides, most pc games take as long, if not longer to develop than EnB has done, look at doom3, unreal 2, duke forever, the big games take years, red alert 2 was 2 and a half years old when generals came out, and generals was in production (not just pre-production) before ra2 was actually released (admittedly very early stages, but thats not the point)
guaging a game on wether it breaks even on retail is unfortunately a thing of the past, the games success will be (and is being imho) measured by the numbers of players, now and in the coming 2 or 3 years.