JC, I'm not sure if the number of options could, would, or, should increase over-time. Decrease is likely more realistic, whether from tree encroachment as you said, or, the one I like, the evolution of a bunker/hazard that has become so narly, advoiding it completely, is the only prudent option.
Increases in the number of options probably are only achieved from the improved technology in I&B. Since, no one is dicating which type of clubs to carry, be it era or style, the only thing limiting, is the firmness of the turf. If that continually gets softer and softer, the options seem to be but a few. Aerial