How to make an undecidable malware

Fred Cohen in 1986 has proved in his Ph.D. thesis the undecidability of viral detection (no perfect virus checker can ever exist).

My question is : Is it possible for a malware to stay very long time (or forever) under the radar (remains undecidable) for the antivirus industry ?

• If yes, what are the different ways to achieve this goal (perhaps make the behavior of the program chaotic or adding time complexity...) ?