Shawn, the CMT 50 series (48-Volt phantom powering with output transformer) was still being manufactured in the early 1980s, that's true. The CMTS 501 stereo microphone, which was part of that series, had some limited production even in the mid-90s. But I'm fairly sure that the 12-Volt models (the CMT 30 and 40 series) were discontinued just a few years after the Colette series was introduced in 1973.
The main reason for this is that the CMT 50 series microphones drew less than 1 mA apiece, while the (transformerless) 48-Volt Colette microphones drew 4 to 5 mA, which at the time was too much for many recorders, preamps and mixers. As a result Schoeps kept manufacturing the CMT 50 series for the sake of their customers who needed a lower-current microphone.
But the 12-Volt models were simply superseded by the corresponding Colette-series models (same numbering down the line, with "CMC" in place of "CMT"). They drew the same amount of current, had similar specifications and sound, and at the time, you could even have your CMT-series capsules from the 12-Volt series mounted in Colette-series housings when you changed over to the new amplifier type. A lot of film and video sound people did that because they wanted to use active cables, which were patented and still unique to Schoeps then.
--best regards