RSLinx 2.59 was the last revision of the 2.5x major revision, which had a very long product lifecycle of about ten years.
It *should* still be able to recognize modern 1756-ENxT EtherNet/IP modules and modern ControlLogix controllers, but it would not have their EDS files installed by default.
Right-clicking and selecting "upload EDS", or otherwise loading EDS files from Rockwell Automation using the EDS Hardware Installation Tool should allow RSLinx Classic to recognize any ControlLogix CPU and Ethernet module.