I have not been anywhere in Thailand that refuses cash - yet - but if and when that happens I won't be surprised and I'm expecting to encounter it sooner, rather than later.
Don't forget, the Thai government is encouraging a "cashless society" so they certainly will support use of these electronic systems. Besides, use of these systems is probably a hell of a lot less expensive than printing and minting money.
If nothing else, cash can be misplaced, lost, pickpocketed, counterfeited, or otherwise stolen. It's a little harder for criminals to get their hands on other people's money using systems such as PromptPay, so in my opinion these systems are much safer than carrying a lot of cash.
I don't know why they haven't gotten rid of those useless satang coins long ago. I would think it costs much more to mint them than they're worth. You can't even save them up and then cash them in at banks. Banks don't accept them despite the fact that it is Thai money. Convenience stores usually will still cash them in for you, but who knows how much longer. Try giving a big jar full of them to a Thai boy you've offed as his tip - but be prepared to duck when he punches you right in the nose . . .
What Bangkok location are you talking about in your post?