CD singles will be phased out in the US within three years, according to a leading chart expert.
Single sales in the UK are down 30%
Sales are continuing to drop with online piracy blamed for many of the industry problems.
With broadband becoming far more common, it is easier to simply download a track than go out and buy it, the industry argues.
Emmanuel Legrand, Bureau Chief for Billboard Europe, told BBC World Service's The Music Biz programme that this is likely to spell the end of the chart single.
"I doubt that in three years from now, there will be physical singles available in the US," he stated.
"It will happen very quickly once all the legitimate services will be in place."
In the UK, sales CD singles fell by 30% last year.
For the first time, sales of the most-downloaded track in the US have been higher than those for the CD single at the top of the Billboard Hot 100 singles chart.
A number of factors are coming together to further promote the growth of online music - and hasten the demise of the CD single, Mr Legrand added.
"This business is growing," he said.
"The introduction of iTunes by Apple has made a huge difference in the way that consumers pursue legal downloading - iTunes probably accounts for 50% of the downloads.
"When Microsoft launches its service, and others join the party, we will see the volumes are going to be huge."
He added that he felt the technique of releasing singles to promote an album was failing.
"The single is actually going to cost you money, because of the size of the country, because of the promotional push that you have to put behind it," he said
"So their calculations were, 'if we do all this only to sell singles - and we're not going to make money on singles - we'd better put emphasis on albums.
Mr Legrand said peer to peer services had taken off because it allowed people to choose individual tracks rather than whole albums.
This is an argument often used by people who illegally download music - that albums are too expensive for the two or three songs they really want.
This aspect of choice is crucial for legal download sites to be successful too.
"The internet allows consumers just to pick the one song they want," Mr Legrand said.
"I think that flexibility is going to be reflected now in the charts."