Just got a catalogue in the mail from a local music store.
It has 23 synths of various kinds from pretty much kiddies toys to some reasonably serious kit. It also has 48 guitars, 12 drum kits, innumerable guitar pedals, 2 violins, 2 flutes, 2 trumpets, 3 saxs, 2 clarinets, 2 recorders, some other percussion, a few microphones and headphones, and lots of amps.
I think the guitars have it...
While I do see an increase in synths over time, I don't see a decline in guitars. I think the synths are additional to, not replacement for, guitars.
--=-- My credo:
If it's worth doing, it's worth overdoing - just ask my missus, she'll tell ya
--=--You're only paranoid if you're wrong!