I suspect it will not be a language in the traditional sense. Instead of describing how to build a system, it would describe the system's entities, relationships, goals, constraints, NFRs etc... The application model becomes the source of truth, and the code will be the generated artifact. A single spec defined and code generated will be optimized for web, mobile, desktop, api, etc...

The spec itself can be in a yaml type format or a hierarchical knowledge graph...