Won't happen.
At this point the 'death' penalty is given to extremists and also to alleviate the pain of those affected and who want the harshest justice.
Like the article said, the last execution was more than a decade ago, and this guy is the 63rd on the death row. Meaning he is more likely to die of old age while living in ADX Florence, Colorado. This will be his cell, the same type Dzhokhar Tsarnaev is living in right now while awaiting his execution which won't happen:
