Negative interest rates don't just magically mean everything to do with banks operates like it's opposite day. Negative interest rates do not mean someone pays you to take out a loan. It only means banks pay the central bank for not making loans.
Paying average people to take out loans is quite possible in a cashless world. If the central bank is "giving" a rate of -8% to banks which deposit money with it, a bank can earn a profit by loaning out the money at -2% (i.e. losing 2% a year is better than losing 8% a year, for the bank.)
For you, it still doesn't make sense to accept the loan, unless you have a special reason. If you have no compelling reason to borrow the money, the best you can do is to park it in the bank. But the loan only pays you 2% a year, whereas the bank will charge you a likely 12% a year for that money. So, the same principle applies as today: borrow only for special reasons.
In a cashless, negative interest world, the part of the math that matters is higher vs. lower (i.e. being less negative is higher.) The higher-lower comparisons will remain the same. Where the 0-mark is relative to the various rates, is irrelevant.
Just an elegant way for the elites to continue fleecing the public.
First, your assumption uses rates that are nowhere near reality. All CBs that have negative rates are between 0 and -1%, and at rates that low below zero, the banks are just going to eat the loss. No one is loaning money out at negative interest rates, and if rates went so negative that ever became a viable reality, the economy would be so jacked up that there likely wouldn't be any liquidity to make loans at all anyway, because the lending economy would be completely paralyzed with fear of moving money at all.
Second, if the bank is charging you -2% on the loan, that means they are paying you 2% to take out the loan. So it wouldn't matter if you had a legitimate reason to take the loan out, because you would make money for doing so, so you'd take the loan and park it in a mattress and be better off. But this is not a viable happenstance anyway because banks are not giving you interest to take out a loan, so the issue is moot.
Third, banks will continue to eat the loss because they have to be competitive. No bank can get consumers to agree to pay to deposit their money unless
all banks were doing it and consumers had no choice. And even then, the consumers would have the choice not to deposit their money, and that eventuality would sap much-needed liquidity from the banks and threaten the banking system, so no CB is going to push rates so negative that passing on negative rates to consumers becomes a likely outcome.