Credential, meaning something signifying worthy of faith or belief, is a word with a distinguished heritage, likely derived from the Proto-Indo-European word for "heart", "to believe," or "put one's heart." As everyone knows, except perhaps a few liberal arts profs, awarding credentials is one of the primary businesses of higher and other education. Students, parents, and legislatures put their faith, money, and heart into education so that their children and society generally, will be enriched by achieving these credentials.
Coursera, the biggest MOOC, has just made a major move into continuing education for educators. This is an opportune time, I suspect, since they hope to take advantage of the big move to the Common Core standard. Teachers are one of the principal consumers of continuing education, so this is a big business area especially for State universities. Teachers are big consumers of continuing education since they pay is closely tied to post graduate education. If school districts and States will sanction Coursera's classes for teacher credit, teachers will flock to them. Expect a big push in that direction, and a big pushback from schools afraid of being passed by.