Originally posted by D1N0 Mainstream
dslr: three brands Canon Nikon Pentax
mirrorless: four brands; Sony, Fuji, Olympus Panasonic (and Canon if you take their m camera's seriously.)
That is not that many. 7 brands, 6 mounts (well 7 if A-mount is not dead) Other brands are niche or luxury players.
Canon has three mounts, since aps-c doesn't fit fullframe and m.
Pentax has K, Q and 645
Nikon has F (aps-c and ff lenses) and 1
Sony has A and E and both aps-c and fullframe lenses.
Hasselblad has two mounts.
PhaseOne is there.
Leica got way to many. M-mount is the important one.
4/3th and m4/3th are still around
Sigma has SA.
Fujifilm has X
Samsung NX (while dead) is still a little around, their NX mini has disappeared.
We could do with less when the market will shrink. Nikon and Canon maybe come with mirrorless fullframe. Fujifilm maybe enters mirrorless 645. Olympus is maybe doing something with mirrorless fullframe, but that might be joining in on Sony.