Well, could they? We've seen a few failed attempts like the Ouya and various other Android based 'systems'.
But if a company like Apple or Google or Valve or whoever wanted to make a new system and could throw a ton of money behind it, could a new video game system actually compete with and outdo the likes of Sony or Microsoft or Nintendo?
Anyone can make a system. I mean there is a Big Three as I've heard it called, but really if someone from SEGA said, "Hey, I have this idea for a system and it *does something innovative* and *does something cool*," they could totally make a new system. It may not get popular, but any company could make a system. The only thing is, they would have to have 3rd party support and that's pretty hard to find so your first party stuff is going to have to be good.
I mean they could, but I don't think it'd do very well. It'd have to be pretty out there and different, and able to get both a lot of third party support, and really slam out it's own first party games to get any notice. I also don't feel like the market could really handle 4 major consoles; most people buy two at most. I think it'd either end up a copy of the PS4 of Xbox One, or something off the wall like the Wii U (And we've all seen how well it's been received). I just don't think there'd be any chance in hell it'd succeed right now.
