So I tracked down the answer on this, and want to post it here for posterity's sake. Microsoft is updating the program guide so that MTM (Metrics That Matter) evaluations are still credited, even if they don't come from students of a Microsoft Partner
or IT Academy. In other words, it's a non-issue according to Microsoft's MCT Team. When I pressed for a publish date on the new program guide, I was advised to 'watch my inbox' for communication on the matter.
For anyone that's curious about the details: It's on page 3 of the MCT Program Guide, specifically item
4.1 - Compliance. As of this writing, it's the third bullet point regarding delivering one training per year with associated MTM scores in order to meet the requirements for renewal of one's MCT. (I heard a rumor that it will be
upped to 3 trainings per year, with an average score of 7 or above to renew your MCT).