Ok, I see a lot of false info in here. EE chiming in here.

Minor efficiency improvements: consumer electronics, batteries, solar panels, CPUs/GPUs

Major efficiency improvements: power transmission, wireless power transmission, electric motors, high density electro-magnets (used in fusion, MRI, etc), 'traditional' energy generation techniques that spin a thing to produce electricity (wind, nuclear, hydro, gas, (even coal, but let's pretend coal doesn't exist)).

Outside of my expertise, but I'm speculating major improvements: wired and wireless data transmission (antenna tech)

The implications that excite me the most are mostly around transportation.

-Realistically, of existing technologies I think electric motors are the biggest winner with superconductors. For the most part, the size and power of electric motors are constrained by how to get the electrical waste heat out. With superconductors you don't have electrical waste heat. You can create incredibly small, powerful, efficient electric motors with super conductors. This means efficiency gains in so many of our big 'energy sinks' right now. Transportation, air conditioning, manufacturing... I mean it would be a largely unnoticed improvement to almost every aspect of our modern lives.

-Cars with close to 100% regenerative braking (superconductors+capacitors for temporary energy storage) You could stop at a red light and accelerate back to the same speed 'for net-zero energy'. THAT IS BANANAS! A current conventional gas car burns fuel for ~30% efficiency, the other 70% is waste heat. Then after you've done all that inefficient work to get moving you hit the brakes and USE FRICTION TO TURN YOUR MOMENTUM INTO MORE WASTE HEAT! Bugs the bajesus out of me! Superconductors would make it much more practical to recoup energy when stopping a vehicle.

Then you can get into cool new technologies:

-Mag-Lev trains would be super cool. I don't see a huge practical benefit since the mechanics of train wheels on rails are pretty efficient as is, but come on... levitating trains? so cool!

-Rail gun style space launch systems (unfortunately, this comes with rail gun style weapons too, sorry everybody!)

-Tokamak nuclear fusion reactors are currently constrained by the strength of the magnetic fields they can produce using electromagnets. The limiting factor is largely cooling for these electromagnets and the associated superconductors. Room temp superconductors allows for much more compact designs for the magnetic confinement infrastructure used in these facilities.

-You could make a friggin mag-lev skate park. Hoverboards! REAL FRIGGIN HOVERBOARDS could be produced!

-(I think) We can actually start talking about 'active support' structures. Buildings that would not be possible because of the compressive or tensile strength of known materials can be supplemented by active support through electromagnets!

-This removes probably the biggest constraint in electrical engineering and design. We will see amazing technology come out of this that none of us can predict.

EDIT (I'm just gonna keep adding these as they get mentioned elsewhere):

-Magnetic energy storage. Similar to how an electrical transformer works: You induce a current to flow which 'stores' the energy in a magnetic field. In the case of magnetic energy storage you just leave that current flowing. No resistance means it will flow indefinitely. You can then extract it directly or through interaction with the magnetic field.