So this is what Alexander from WatchAdvisor posted in the comments section of a recently uploaded "Speedmaster beauties" review:
the Moonwatch
will now get a new Master Chronometer certified caliber... then the mission is completed and all Speedmaster are powered by the new generation movements.
Not sure if this is a completely accurate statement, but Alexander seems to have a good relationship with Omega, at least based on some of the previous interactions/interviews I have seen with their executive staff.
So, if this new Speedmaster Pro caliber is really METAS certified, will it be a new automatic 3-dial chronograph caliber or just the existing 1861 with "upgraded" anti-magnetic materials?
As we saw this year with the 1869 on the Apollo 8 DSOTM, Omega are apparently being allowed to implement decorative and material changes to the "Moonwatch caliber". IMO a new automatic caliber is more likely.