No way, I personally don't expect any of the consoles even reaching 50million, the structure of the gaming market is changing so fast.

Very difficult. Anyway, we'll be able to make lifetime predictions that make any sense im 4-5 years, not earlier. Judging just from Wii's first three years we could have predicted 160M or more in a 10yrs lifecycle (including 3 years as cheap model after next gen launch), and it would have been sensible IF things kept on going so good, but Ninty shot itself in the foot, killing Wii too early, and the Wii brand with it, so killing not only Wii, but making Wii U be born crippled too.
Even if Sony won't shoot itself in the foot too (we know it will, it always does it in some of its divisions , but probably it won't with PS4), nothing can grant us now that both things depending on Sony and those out of its control will keep on going well enough.

People also don't seem to understand that the pre-launch E3 hype that fed PS4's surprising launch sales, are going to continue to cool and slow. There will be dips and valleys, like anything. But some folks around here seem to think PS4 is just going to keep selling 100k+ every month from now till the end of time. It won't, guaranteed.

I seriously doubt it and I don't care if they go bankrupt.

100k a month? It sells more than that in a week. You must be thinking of wii U. Also the sales will be evrn higher in the following years with the release of heavy hitters like Uncharted and Gran Turismo anf other 3rd party titles improving the overall library as well as a price drop here and there.

I dont think Ps4 will reach ps2's ltd hardware sales but it definitely will have a similar market share,  with Xbone being little over original Xbox and Nintendo sinking even lower than Game Cube, below 20% market share