Technically the answer is yes.
The restic software is the implementation of a program for writing and reading the restic repository format, which is intentionally clearly documented in this file in the source code repository for restic and its documentation: restic/design.rst at master · restic/restic · GitHub
This means that as long as you have this specification, you can write your own software that reads your backups and restore them. Hence the answer to your question is yes.
It all boils down to what you consider the definition of “can” to be 
Regardless, the intention of @fd0 when he created restic was that the most important thing is a well documented and specified repository format, such that noone should be dependent on his own code, even 100+ years from now. Your worst case scenario is exactly what this addresses.