If society goes cashless, you might be forced to carry a smartphone in order to get food. This could mean the end of privacy. What your thoughs on this?

I mean, that's already the case for the majority of peoples' transactions now. It's a bit late to worry about it.

That said, we have our transaction badges (debit cards) to do transactions, and so long as we continue to use those, there won't be a mandatory requirement to have your phone on you. At the same time, all those transactions are still stored and linked to you by your card provider, so you still lose privacy.

On top of that, everyone brings their phones pretty much wherever they go regardless of transactions, because they're deeply helpful devices. That already gives you telemetry at all times, which can be logged in various systems.

TLDR: The loss of privacy happened as early as 2 decades ago. It's just becoming worse as time goes on.