The existing RF lineup can be roughly broken up into 5 tiers:
Tier 1 - Statement lenses, super telephotos.
28-70 f/2L, 400mm f/2.8L, 600mm f/4L, 800mm f/5.6L, 1200mm f/8L
Tier 2a - Upper tier L workhorse lenses
50mm f/1.2L, 85mm f/1.2L, 15-35mm f/2.8L, 24-70mm f/2.8L, 70-200mm f/2.8L, 100-500mm f/4.5-7.1L, 5.2mm f/2.8L
Tier 2b - Lower tier L workhorse lenses
14-35mm f/4L, 24-105mm f/4L, 70-200mm f/4L, 100mm f/2.8L Macro
Tier 3 - Enthusiast
35mm f/1.8, 85mm f/2, 600mm f/11, 800mm f/11, 24-105mm f/4-7.1, 24-240mm f/4-6.3, 100-400mm f/5.6-8
Tier 4 - Entry Level
16mm f/2.8, 50mm f/1.8
Looking for gaps at each tier gives us some obvious lenses to conjecture, including some already rumoured:
Tier 1:
Wide angle f/2L zoom, Mild telephoto f/2L zoom, 200mm f/2(1.8?)L, 300mm f/2.8L, 500mm f/4L
Tier 2a:
Fisheye L prime, right ultra wide angle L prime, 24mm f/1.4(1.2?)L, 35mm f/1.2L, 100/105mm f/1.4L, 135mm f/1.8(1.4?)L, tilt-shift prime lineup, 10-24mm f/4L, 200-400mm f/4L, 180mm f/2.8L macro, ultrawide fisheye L zoom
Tier 2b:
200mm f/2.8L, 24-70mm f/4L, 70-300mm f/4-5.6L
Tier 3:
20/24/28/40/50mm primes with IS, light macro capabilities, and apertures in the f/1.8-2.8 range. 18-45mm f/4-5.6. Compact enthusiast macro lens (100mm f/4 IS?)
Tier 4:
24/28/35/40mm f/2.8 pancake-ish primes without IS. Ultra cheap standard zoom kit lens, ultra wide, and telephoto zoom
Add in cinema lenses, some more "experimental" lenses like the 600/800 enthusiast telephotos or 5.2 dual fisheye, and few lenses that aren't in line with what Canon has done in the past (20/28/40mm L primes?), and 32 lenses is quite doable.