They're far from dying but I do think they could be heading for rough times if the WiiU never heats up and the mobile market keeps eating into their portable sales. The 3DS is doing well but not as well as the DS, and it could get worse. We shall see.
Sony is actually misleading because while the company is struggling the game division is one of their few profitable sectors, from what I understand.
Microsoft makes too much money elsewhere to really fail but I do find it amusing how badly they enter markets. Have they made an overall profit on gaming yet? I doubt it, even with some profitable years this decade. Still they have the capital to keep holding on and never let go. They don't want to be leaders in gaming though, they want to control all aspects of your living room experience.
The 3DS sold more units on its first year than the DS.