I believe all sales of individual songs on an album on iTunes count as a single sale. So if (for example) everybody starts buying 'Stranger in my own home town' from the iTunes album "Elvis in Memphis", then this song will appear in the charts as if it was a single.
The only difference between this and actually release a single, is that this single can hold a few songs. This single (with these 2-3 songs) can be sold at a special price, while all individual songs can also be purchased separately (just as on a normal album). Also, this single can get marketed better of course than just one random song on a full album.
I still think that the only way for Elvis to be really big again, is for Sony to grow some balls, throw away Tom Parkers "How to manage a superstar" manual, and actual try to focus more on the 1968-1977 Elvis. This is the only period in Elvis' career with a contemporary sound that at least matches todays' sound a bit. It's frustrating for me that so many youngsters only think that Elvis was popular in the 50s with songs like Teddy Bear and Don't Be Cruel, and was washed out after the army, made some bad movies and became fat when he started to perform in Vegas.
Elvis is cool! Elvis is now!