It's a bit more complex than this and I didn't understand it completely, but past tech has been on the order of 14, 11 and 9 nm/transistor. I think this is as large a breakthrough as it is because they're actually building transistors 3D, and when you average out the switch density you get this figure. So the transistors are not actually 2 nm, but they fit that space/area when you look at the complete chip.
Regardless, the biggest issue is not really the transistor count, but rather the heat generated. Smaller is better and this is going to see a 45-50% increase in computation/power, which means less heat generated and less heat needing to be removed.