Everything has a Life Cycle of maturity, growth and decline. Music is a part of the everything therefore it too will continue to mature, grow and decline.
What we will hear is current sounds being forged with older ones to create new ones. New genres continue to be developed per the cycle I just mentioned. Part of the question of what will music sound like in the next decade is directly related (I'm assuming) to what commercial viability these new sounds or genres will have? I am believing that their will be extreme commercial viability for those musicians, recording artists, music producers/composers, singers and songwriters who carve a niche for themselves and give their niche (audience/listener/client) what they want, when they want, how they want it and at the price they want it.
Those people that have a burning desire, a practical written plan and execute that plan daily will most likely see a long and prosperous music career in the music business. Creative artist, musicians and songwriters, etc. that speak to the human existence do so in the vein of "What's Going On?" The lyrics are as much of a reflection of the time as the music (drum). As food, fuel and other consumer goods/services price points continue to rise globally faster than that of our incomes (revenue streams) and human suffering continues I think you'll have more genuine musicians, songwriters and artist who speak to that experience. Out of that you'll have more music that people can feel. People are searching for something more in life/existence and in music.
What I have stated may seem to be a bit off topic, but if we remember when Rap/Hip Hop Music started in New York it started because it spoke to the needs of people who were suffering and wanted to convey/relay "The Message." It started because people were searching for something more genuine that spoke to their experience. Rap/Hip Hop Music borrowed from the old sound of its day -Disco, Poetry/Spoken Word and others and forged a new sound. Will Hip Hop stay dry? Maybe it will depending on who you ask and their definition of Hip Hop.
The human experience through music is part of everything and everything has a Life Cycle of maturity, growth and decline. Music is a part of the everything therefore it too will continue to mature, grow and decline. Be part of the new sound that will emerge in music.