Looking at the Mozart Dice Game referenced in the article, it would seem that many different styles and moods can be contained, ready to be selected as needed, and segue neatly with one another.
Adaptive music is certainly becoming noticeable in more games of late. De Blob had an interesting take on this, with a base track that had multiple solo 'flourishes' which could be layed on top, responding purely to player action. Different colours represent different instruments, and the act of colouring objects is the trigger.
It's a very new field and the process is not defined yet, so it's daunting. But it is far from impossible.