Is there some reason why new camera files aren't compatible with old versions of LR? In other words, where does the "translator" reside for each camera's codec - in the LR version or in the Adobe Camera Raw? And if translator is in the ACR, why would new ACR 8.7 not work with LR4? Are all .CR2 files organized in the same way, with just the exif information varying between camera models.
I am feeling irritated about obligatory update to LR5 in order to process Canon 7D2 files. Yes, this means moving stuff around, then updating the operating system to the only one currently available (10.6.8 directly to 10.10.2 Yosemite), which means my user-installed non-Apple SSD boot drive is "screwed" because Yosemite doesn't allow TRIM SSD disk utility for non-apple SSDs to work without dropping ALL security extensions (kexts), which means I would have to swap out the Samsung SSD boot drive for the old spinning rust currently doing duty as spare off-site backup drive in the safe deposit box. Or, just leave the security extensions open to the outside world via a kext management app TRIM Enabler, and don't go online (I don't use the laptop online much but I do do so occasionally - one can raise the kext barrier with reboot). That will teach me to keep more current.