Even the 3DS doesn't GOW that low, but I can see bundles for $150- coming in 2019.

Yeah I can't see a $99 PS4.....

At least not in the near future. Shipping, warehousing and raw materials costs don't drop when components prices drop, that would be easy, but when the device size and package shrink. To get that low, PS4 should shrink to a size little bulkier than a compact Blu Ray player, and this will require a huge drop in power consumption, as it wouldn't make sense to shrink so much to need a more expensive coooling system, partially wasting the saavings.
If and when such shrink will be viable, PS4 uses a very mainstream x86 PC-like architecture, so on a mass-produced device, well, $99 is still a difficult goal, considering that it needs a HDD or SSD too, but considering how low consoles with just an optical drive could drop, and adding a cheap HDD, $130 could happen.

110 million are possible lifetime, i think.

Sony will cut the price and keep selling Slim at low cost, then Pro will start dropping price and many old users will Switch to Pro before Ps5 arrives, 110M is definitely possible and should be broken. 

I think it'll end up more around Wii/PS1 sales.

130 million hardware, 1.4 billion software. That's my estimate.

Ps5 will release in 2020/2021 most likely. Ps4 will have a super slim version by then and it will still be selling well in 2021/22/23. I give it a chance of getting as low as $99. $129 is very doable though.

Sony will be keen to get ps4 as cheap as possible for after the ps5 release to grow the brand in regions like eastern Europe, Africa, south America, India, China etc.

Its possible :)

1,4 billion software, that is insane! But maybe someday, yes : )

Amazing sales, but i still believe it can still be better when God of War, Spider-Man and The Last of Us Part II come out. Those 3 are the biggest PlayStation game since Uncharted 4 imho.