120m is guaranteed, the question is how close can it get to or surpass 130m.

I'll stick with 125 million.

OH! I voted and then saw it was the most popular option. Probably a slight low ball. As for your bonus question, I don't have to disassemble my system and spray poison on it every 6 months so it works properly, so I'm fine with a subscription that is required for MP, and has netted me 500+ games across 3 systems.

....I have to add though...That the Vita has totally screwed me over. I'm kinda famous for it in my PSN circle, and have mentioned it here. One or thirty times. A nightmare.

17.8 to 13.6.
That's 4.2 million.
That's a pretty steep drop. About 23.5%
If that same drop holds for the next 12 months, that would mean the PS4 would ship 10.4 million units from April 2020 to March 2021, bringing its lifetime shipment totals to 120.8 million units. That's a drop of 3.2 million units YoY.
But because of the impending launch of the PS5, that drop will be significantly higher. I think the next drop will be roughly 30-33%. That would put the next FY shipment somewhere between 9.1-9.5 million. Just under 120 million.
So, 120 million is the floor. But I think 130 million is the ceiling. I'm guessing somewhere between 125-127.5 million will be the final mark.

Bonus Question: I don't have PS+ subscription and I don't play online multiplayer as a result, so I don't care.

A little bit under 125m

As for bonus question, paid online needs to go and gaming community needs to take a stand to make companies to drop this policy.

Before the quarantine started i would've predicted 125m, now it's very hard to predict. It can't go much over that, it's the end of the life for PS4, but it could possible get to 130 million and maybe a bit over that.

Right now i'll just say 125-130 million, closer to 125 million.

I'm still sticking with my 130 million prediction, as there is little to 0 chance the PS4 won't manage to do another 20 million LT.

130m atleast.

I think PS5 & XBX are gonna be 500-600$.
That ontop of the current economy is gonna hurt next gen adoption rates.

If PS4 is lowered to like ~149$ (perm), I could see it selling pretty well for along time.

Final sales number really depend of what strategy Sony takes with PS4 in its final years. It’s been more than 3 and a half years since the last price drop for the system (September 2016).

As comparison, the PS3 received it last price cut on September 2012 ($269), more than a year before the launch of PS4. Ps3 did around 8.2 millions in 2013. PS4 is doing 3.6 millions in 2020 (1 million more compared to What the PS3 was doing in 2013 in the same time gap), so PS4 can do a little bit more than 10 millions for 2020.
However, that depends of how much is the price cut Sony will do, $50-100 and when.

But, it would end around 130-135 million units.

As I still predict no price drop, and a competitive PS5 price, I will stick to my prior prediction years past of 115-120m. Of course it will be much closer to the 120m than I expected, especially with the coronavirus boost. I wouldn't mind being wrong if it instead sold 120-125m, as my first prediction was actually 115-125m, but then I lowered my expectations.

Either way over 125m seems daunting, if not impossible with Sony's current strategy.