Apple discontinues products on occasion (hello, SuperDrive), and Apple regularly replaces products with an updated version (hello, iPhone). But I can’t think of the last time they discontinued a product months before an announced replacement arrived. Their MO is to keep selling the old until the day the new takes an over. I mean, they will let stock dwindle and such, but they don’t outwardly discontinue it.
The closest I can think of is the iMac Pro, which I think was discontinued for about a year before the Studio and Studio Display were introduced. But that was part of the whole pro line debacle in which nothing was standard MO.