Photoshop has traditionally had the Select > Color Range command. There is also HSL keying inside the Hue/Saturation adjustment toolset, which, annoyingly cannot be used to create selections for use with other commands without clumsy workarounds (that I know much better than I would care to admit).
What I am hoping to see is a non-destructive way to do masking based on luminance, HSL tools, as well as possibly more sophisticated keying algorithms that are found in video software (Primatte, Keylight, etc.). Most video-focussed color correction software (DaVinci Resolve, Speedgrade, Lustre, Baselight, FilmMaster, Assimilate Scratch) allows for non-destructive HSL keying already.
The most elegant way I can imagine this working inside Photo is that similar to regular layer masks, a new procedural mask layer type for non-destructive HSL/Select Color Range masks with adjustable parameters would be available. Like an adjustment layer, except that the result would be a mask instead of an RGBA image, to be used just like regular layer masks.
That way, it would be easy to adjust the selection parameters interactively after the fact, and, if need be, rasterize destructively to a regular raster mask layer. In additions to the keying in Luma, RGB, HSL, YUV and LAB, parameters for blurring the result, expanding/contracting the mask would be useful. The exact same functionality could then double as a vastly improved "Select Color Range" command as well.