Ugh, I hate that Digital sales aren't tracked because from here on out retail sales are always going to decrease and not knowing digital sales paints a very one sided picture that the market is declining.
Just look at PC. Retail sales are abysmal, but if you track player counts for games like BF4, PC is usually not far from the top. So I don't think a decline in retail sales, especially compared to a month last year that actually had a new title released on PS360 (DmC) to no "new" title this past month, is indicative of anything until we know how much digital sales make up. I mean if Nintendo can sell nearly a 100,000 digital copies of Fire Emblem (on a system with no account system), I think it is fair to say other titles can do similar or better numbers on platforms that are a little more digital friendly.
But since there are no numbers, people will just continue to believe the market is in a decline, despite having two of the most successful console launches ever, both of which offer every game released digitally.