Modules can then be views and I think they would still be useful. I think the coincidence we currently have where modules are files makes it seem like mutual exclusivity and tree-like hierarchy is a defining feature of modules. We can throw that out. I think a lot of Joe Armstrong's complaints go away now.
Modules are still useful for human purposes. They are useful units of responsibility, accountability, maintenance, learning, and presentation. In fact, these facets of modules are enhanced if modules can intersect as views into a codebase: Overlap and dependence of code can be modeled as intersections and joins of modules-as-views. That these can be computed from the structure of code rather than implicitly understood on top of the directory hierarchy of a file system, or worse, forcibly mangled to fit into a tree-like hierarchy like files is a tantalizing possibility.