The data miners at @Pokeminers have made yet another discovery; Shadow Zapdos and Shadow Articuno have been added to Pokemon Go's Game Master
This means that we are likely to see these two Pokemon added to Giovanni's lineup in Team GO Rocket content.
While we don't have absolute confirmation yet, it seems likely that Giovanni's legendary Shadow Articuno will be replaced, possibly in rotation for the beginning of December. If this is the case, we will most likely see Zapdos join Giovanni's lineup soon, as it is next in line in terms of both name and dex number.
It seems that Niantic is planning on making Giovanni and his shadow Legendary Pokemon the big draw of Team Rocket content. But this also brings with it a bit of speculation: does Niantic intend to only make the Legendary Birds available? Giovanni has a strong connection with the legendary Mewtwo, so it's possible that we'll see the Genetic Pokemon added in Shadow forme eventually, possibly even Armored Mewtwo. Beyond that; who knows what other Pokemon Giovanni could pack in the future? The precedent set by a potential rotating Legendary for the big boss of Team Rocket could be very exciting. Let us know what you think in the comments below!