Today when Microsoft has announced its latest gaming console, Xbox One, everyone was hoping that it will be able to play Xbox 360 games but Microsoft has denied it and said that it wont be able to support.
Actually in press event Microsoft remained quite in this matter but in Q&A session The Verge has asked about it and Microsoft has said that it was an technical issue because Xbox 360 was based on the PowerPC architecture while the Xbox One is based on x86.
Sony too facing similar issue too with PlayStation 4, but it has said that they are working on it and it will support backward compatibility with PlayStation 3 via could based streaming.