Hi and welcome to the forum!
Skeletons and Zombies are one of the most important units of the VC army. With the current rumours, it appears the Invocation of Nehek gets nerfed. The Invocation of Nehek is a very important spell for the VC, meaning that you'll end up raising a lot of Zombies(and Skeletons). Though, why buy 100 Skeletons/Zombies(/both) and then use only a part of it when the new army arrives?
Even though the new army is 6 months away, as well as the probability that the stuff can change overtime, is still a big differenence in money.
It seems that Necromancers can raise a lot of unit types, perhaps only adding to units (who knows?), and Vampires Zombies (but can raise units... again, who knows?).
VC armies now would use around 40-60 Zombies (raising) and about 20-40 Skeletons for direct fielding.
This varies though.