I think the main issue for programmers is VCS, and the associated tooling like diffs. With git + code, you have an easy way to modularize, diff, collaborate and review. In these other professions, you mostly work alone or go through the painful process of working together on the same project.

This shouldn't be impossible for flow-based tools, either by making them collab based (like figma) or by having multiple representations (declarative code and visual - possibly by having visual be read-only).

Flow based programming already have a straightforward and imo excellent path for modularization (which is the only known way to deal with software complexity). I would love to see flow based programming combined with individual components written in conventional languages. Regular code is clearly superior for many tasks, so flow should be applied between components, and not be too granular.

Another challenge is meta-programming. If you need to produce components at runtime, you would naively lose visualization and other benefits. So more research and idioms are needed to really present a coherent system that maintains a similar DX when that extra flexibility is needed.

Still, I'm very bullish on medium-term applications of flow based programming within software design. At least for me, it has some absolute killer features; such as understanding existing systems, mapping to my mental model better and spotting bottlenecks and inconsistencies much earlier. I already use pencil-and-paper flow diagrams for software design, but resort to conventional code when implementing.