Assembly developers often struggle with editors that are either too complex or lack necessary low-level features. You'd build a streamlined editor with syntax highlighting, debugging integration, and performance optimization for assembly code.
Freelance or professional assembly programmers would pay for a tool that saves time and reduces frustration. Start with a basic editor supporting a few assembly dialects and expand based on feedback.
The biggest risk is the small market size—assembly programming is a niche within a niche.