Yep. The trend is definitely mirrorless, but for those with no need or desire to switch, the glut of used gear is a GREAT opportunity to pick up fantastic bodies and optics at bargain prices. Many older film SLR and dSLR lenses can be used on mirrorless bodies with adapters, albeit with certain disadvantages (no AF or slower AF, no auto aperture, no data coupling...). So those used lenses won't be around forever. Grab 'em while they're available.
I say to trade in hardly used gear so that others can use and enjoy. Nothing wrong with mirrorless but nothing wrong with DSLRs either. These are all cameras!!