1. Complete the micromasters courses at your speed.
2. Get a passing grade in a proctored exam.
3. Get accepted to a masters program with 1/2 of your credits taken care of.
4. Finish the masters degree on-campus.
I can see this being great "marketing" for the university too though -- once you got the "micromasters", the only way to get half your credits toward a degree is to go to the same university that gave you the micromasters (if you can get accepted, they took your money for the micromasters without promising that) -- they've kind of locked you in.
Coursera has something similar called MasterTrack; there's not a generic cross-platform name for it, though if it is successful for multiple platforms and graduate institutions that will probably change over time.