I'm curious is there a number you think a console needs to sell not to be considered a failure? I think 20 M

I'd guess enough units to profit from it. Depends on how much it went spent into the actual creation of the machine, the marketing and everything else.

Of course, tiny profit isn't better than huge profit; but Economics dictate that as long as you break the barrier of losses and step into the benefits area, it can no longer be called a failure.

If it isn't a loss in profit, it's not a failure

More than all the others.

I guess 20 Million or more provided it made profit along the way

I think the most important thing is that it turns a profit. The second most important is how it sells compared to its predecessor. The GameCube isn't considered a failure with 21 million sales next to the 33 million of the N64, but if the PS3 had sold 21 million to follow the 140 million that the PS2 managed, that would certainly be considered a failure.

Since all three console manufacturers had a very strong performance last gen, I think anything short of 50 million ought to be considered a disappointment.

8.4 million

Also obviously depends on it's predecessors. The Xbox 360 sold like what, 85million? Then I think it's fair to say that the XB1 would fail if it would end at 40mil.

60 mill

Maybe when the games released on a system can sell enough to become profitable. How many console sales will enable a decent game to sell enough to turn a profit thus making sure neither are a failure. Is KZ:SF 1.73 millionish sold on 8+ million PS4's enough to turn a profit?