I would suggest a revival of DigiCash, Chaum's original attempt at deploying a digital cash infrastructure in the 90s. Digital cash is not some anarchist fantasy, it is a way to secure electronic payments and to enable electronic payments to replace physical cash (in ways that are currently impossible). A digital cash system that uses a central currency issuing party can still solve the problems that digital cash is supposed to solve: privacy-preserving payments, protections against fraud, secure offline payments, etc. Bitcoin does not even solve that last one: there are no secure offline payments with Bitcoin, nor can there be, and we knew there could not be such payments before Bitcoin was deployed:
In a sense, Bitcoin has ruined digital cash, by stealing the attention of people who might have been early adopters of a DigiCash revival. Now everyone thinks the digital cash is Bitcoin, and so any other system would be forced to either compete with Bitcoin or to reassure everyone that digital cash is possible after Bitcoin's potential (i.e. near certain) failure.