As I know, Spark works like Bitcoin, it's an open protocol and no vendor lockin.
Discussion
Where is the Spark Service Provider source code? Without it third party Spark Entities are not gonna happen.
But above all I’d prefer to not share payments data for first my 20 dollars. Especially when I get LDK’s privacy once I open a channel.
Ok, it's all about tradeoffs, but I think most normal people, a Spark kind solution make more sense. Ecash providers will not want to have the responsibility to keep a lot of peoples money and many providers will have an incentive to steal the money if is too much. And if the police finds one provider and arrest them, other will fear and stop providing the service. It's what I think.
Most normal people use banks, fintechs and credit cards. Even if fiat were to disappear and they had to use bitcoin, why would they change to a wallet?
Re ecash providers getting arrested… we have yet to see evidence of all mints shutting down due to legal risks. I would not operate a mint myself but am happy to pay a fee to someone that does.