So Blackwell is still manufactured in the N4 node, which is kind of surprising, but it kind of makes sense feature size-wise since the N4 node used in the Ada GPUs and the high-density N3 node have more or less the same MT/mm² count.
As for the power consumption of ~ 40,000 Cuda cores running at similar frequencies as the last gen (which could reach a 700W TDP in SXM), that is anyone's guess.