Realistically, companies keep making older generation tape drives for a long time, for example, HP LTO-5 drives are still widely available from normal vendors like Newegg. And except for one discontinuity that's pretty clearly due to the change from metal particulate to BaFe, which is at the heart of this patent dispute, LTO offers two generation back read capability, and one generation back write capability: https://en.wikipedia.org/wiki/Linear_Tape-Open#Compatibility
