AI can't tamper with physical evidence. It can't fake financial records or witness testimony. Many kinds of audio and visual recordings will still have sufficient authentication and chain of custody to be worthwhile.
The main kind of evidence that these AI generators makes untenable are the ones where someone just shows up and says "look at this video of X confessing to Y that I happen to have," which was never a particularly good sort of evidence to base a court case on to begin with.