I don't think a GTX 1080 Ti will command much, but given the reasons above, its Maxwell predecessor, the GTX 980 Ti and corresponding Titan X, may command a surprising premium years later.
Why? With the way things are going now, those top-tier Maxwell cards are the last ones to feature native VGA output, 400 MHz RAMDAC and all. Current DisplayPort to VGA adapters are woefully inadequate of driving high-end FD Trinitron or Diamondtron NF CRTs to their full capabilities; they just can't handle the pixel clocks required, on top of potentially adding some input lag for the conversion.
As for software support, I've noticed that the following tend to be particularly sought-after, for reasons I can guess:
-3dfx cards of any kind (Glide support, nostalgia)
-GeForce 6800 Ultra (most powerful Win9x card IIRC)
-GeForce 4 Ti 4600/4800 and Radeon 8500 (most powerful Mac OS 9 cards)
-GeForce 7800 GS, Radeon X800 XT/FireGL X3-256 (most powerful AGP cards in general, often flashable for OS X use)
-Gravis Ultrasound and deriatives (sample-based synth as opposed to the AdLib/Sound Blaster FM synth)
-Sound Blaster AWE64 Gold (high SNR for the era, S/PDIF output includes PCM sound effects if you want even better quality, will actually fit in most cases unlike early AWE32s)
-Aureal Vortex 2 AU8830 derived sound cards (only way to get A3D 2.0, Aureal SQ3500 Turbo has a neat DSP daughterboard and is especially rare to boot)