Unless there's a sudden major interest in some specific model(s), do to artist usage or endorsements. I think their relative values, will be equal to their original percentage differences, price wise. Couple that, with their overall Great quality, and they will continue to do well, in the 'used' market. But, so will 'Elitist' Epiphones, since all but the Casino, are not made, anymore. They're not! They will retain their value, and even appreciate, to some extent, along with inflation.

That's Not to say, any Gibson is a 'bad' investment. Many Gibson USA guitars, being made these days, for them to retain anything but 'inflationary' value. Well, I think that's more true, with CS models, and limited, or special editions. Someone who plans to keep the guitar for life can easily save the $700 and be happy but for someone who sells their guitars every few years the hit that you would get with the Epiphone in comparison to the Gibson would be huge.