Although I have been trying to keep up a carded collection of the OT figures from the vintage collection as well, I've kept all the TVC (and VOTC, VTSC, etc.) cardbacks as well. I seem to end up getting extras of many of the vintage collection figures (particularly "ultimate" versions and/or army builders), and I think I've kept all of those cardbacks. Just something about that vinty look.
I used to keep all the cardbacks, but did a big purge a few years ago and trashed most of them. With the archives available online anymore, it doesn't seem necessary. I've kept all the VOTC, VTSC, TVC, etc., and I think I kept the OTC cardbacks as well....but the majority of the rest have been gone through and gotten rid of. I actually have a pile of larger vehicle/misc boxes in our garage I need to go through as well. Not sure why I keep them, just do. I think I'll always keep the vintage styled stuff though.