No reason why they would, the 5800X3D's launch price was $449, and the prices remain high. Zen 4 will launch 3-6 months before the vcache variants, it's not long enough for the prices to drop. L3 cache is expensive to produce.I didn't realise Vcache pricing has been announced already... for all we know AMD could release a full range of SKUs with Vcache for a not to dissimilar price than the current line up.
Assuming an 8 core CPU + vcache competes or is ahead of the top CPUs from Intel in games, they will be able charge a lot more. Prices for Zen 4 are most likely to reduce near to/after Meteor Lake's launch.