Most big companies (Avast,Kaspersky, ect) use some sort of Machine Learning ("AI") when scanning for new malware. They just don't rely 100% on it like this new products that market "Artificial intelligence" as a "perfect god" that will remove all malware from the world. That's just their marketing plays to put themselves on the market. Signature will never be obsolete., because there is no best between Signatures/heuristics(Static analysis), behavioral analysis and Machine Learning. All techniques of detecting malware will always have their pros and cons.