https://en.wikipedia.org/wiki/Osborne_effect The Osborne effect is a term referring to the unintended consequences of a company announcing a future product, unaware of the risks involved or when the timing is misjudged, which ends up having a negative impact on the sales of the current product. This is often the case when a product is announced too long before its actual availability. This has the immediate effect of…
It's not like killing the current Mac Pro sales is exactly going to put Apple in trouble - they're raking in money from the iPhone and MacBook (Pro) lines.
This is a carefully thought out plan from Apple for sure, unlike Osborne's blunder.