The battle would then shift to ensuring that the digital legal tender (CBDC) came with a very strong set of rights. Much stronger than we enjoy with the paper legal tender at present. For example, access to the monetary system would need to be guaranteed - even for the criminal and politically unsavoury. There would need to be a "token" where ownership was yours - that is the money cannot be taken from you without your consent or a robust due process. The government could not take your money for taxes or fines automatically, neither could they impose other restrictions on it's use - like convert 20% of your holdings to a "use within a year" token or something. The same with information about how your money is spent; it must be heavily restricted to consent or due process.
I do use cash more than most people in my country. I also maintain a few different bank accounts and cards so that it's much harder for any one institution to gather a complete picture of my lifestyle - though not impossible. While I have favourites, I also shop around a bit for the same reasons. If cash disappeared then I'd widen my net further - possibly incorporating a few foreign cards too. I'd probably barter a bit more too. Maybe do bulk buy trades with friends and family: e.g. each one of us buys an item in bulk and then splits it up for the others.