What about Office Professional 2016?
It costs 400 $.
1. Pretty sure this will go down to 5 GB.....
2. So a customer paying $400 gets the same amount as the guy running Linux and Open Office??

Terms of Service state that they can change the terms, amount of service offered, price of service, etc. at any time and will notify you if there is a change.
As far as Office Professional 2016, yes, you pay $400. You get the "Free OneDrive" account with that, because that's what you get with the Microsoft Account.
Not only do you get the same amount as the guy running Linux and Open Office, you also get the same amount as the guy running a MacBook Pro or an iPad. The free amount is the free amount, whoever you are. The $400 is for Office Professional 2016, not for the "paid OneDrive space", because if it was for paid space, it would have been an amount different than the amount offered to the free accounts.
To me, unless you plan on keeping Office 2016 for more than 6 years without upgrading it, then it's just not a good deal compared to Office 365 Personal. Full price on Office 365 Personal is $69.99 per year so for 6 years it costs $419.94 and you get to pay over time. For this price, you get 6 years of 1TB OneDrive Storage plus 60 minutes per month of Skype calls. If Office 2018 or 2021 come out during that time, you also get the free upgrade and stay up to date longer.
I've actually seen Office 365 Personal for as low as $20 on eBay. Not sure if they are legit. There are ways to get it for as little as $40 per year that I know for sure is legit, and you can stack up to 5 years. If you did that, you'd have a single PC running Office 365 for 5 years for only $200, half the price if you want to pay 5 years up front.
Get Office 365 Home and you get 5 PCs/Tablets/Phones for $99 per year. Even a better deal, since you also get 1TB per user for 5 users.