You could probably do that but it wouldn't be a whole lot better than the existing traces: it's not usually the resistance that limits the size of circuit traces but the mechanical requirements, such as your ability to connect to them and to space them apart so you don't get crosstalk due to capacitive or inductive coupling.
If you could use it to make circuits, especially of a high level of integration then it might well be something much more interesting (Josephson tunneling is briefly mentioned in the article). That could theoretically give rise to very efficient switching gear and if it can be miniaturized enough to efficient CPUs and memory. This is because the typical transistor uses power mostly in the time between the transition between the 'on' state and the 'off' state, when it is acting as a resistor. If you could get rid of that resistance during the transition then you might be able to reduce the amount of power a given circuit uses, but there are still lower limits off losses that you won't be able to escape, so it will not make your CPU magically use zero energy.
Given the contents of the paper such applications are a very long way off and may in fact never happen. Let's first see (1) if it is true and (2) if it is true how well it stacks up against copper wire of the same diameter and commercially available super conductors in terms of cost and practical current carrying capability. If that's all good then this will really be a game changer.
Sometimes the resistance of the trace matters. I’m designing a motor controller that needs to carry 100 amps and the resistance of the copper means that large planes are needed to carry the current without overheating.
Beyond that I agree with everything you’re saying.
That's absolutely true, in power electronics there are applications where the current carrying capability of the traces really matters. Typically you'd either use a very wide trace or some other trick such as via'ing together multiple layers of traces or even to tin-plate the trace. In extreme cases I've seen traces reinforced with solid copper bars.
There is also extra thick copper clad board ('heavy copper PCBs').
