My source is an email from Zeiss to myself answering my question about any plans to make the Z* available in the alpha mount. Not sure how official you would consider that. I'm not ruling out the possibility that agreements can change over time though but this should have been true at the time, about 1 year ago.
Okay, seems like you received a canned response from a customer service rep and IMHO, that means nothing. Such a response is precisely what they would be expected to do. If one could get details on future confidential product plans of a manufacturer, by writing to them via email, everybody would do it.....including competitors.
Until the day such a product is officially announced, they are not going to admit to any such things being in the pipeline. Even beta testers testing an actual product won't admit to it, due to NDAs, until it is officially announced by the manufacturer.