All commercial planes have it at this point. And most part 91 airplanes (General Aviation) have it at this point. Without ADSB you cannot fly in or near class A, B, or C airspace and must stay below 10,000 feet. Which largely makes having an airplane useless for most people.
There are still airplanes flying that have no electrical system but even then some of them have retrofitted a system.
There are still airplanes flying that have no electrical system but even then some of them have retrofitted a system.