Her work's amazing. She's taking the intent and smoothing out the rough edges, filling in the undefined aspects. I've worked with a few really great illustrators and designers as either a designer or an art director. I can't name more than three in the last ten years, and all have been women. She has the rare quality they have of being able inernalize an original vision that's not their own, immediately and viscerall…
I'm in no way saying she would want to do any of this, and I'm not talking about scaling to mass production or anything, but I imagine she could easily offload some of the more common tasks.
Particularly, you've completely nailed that her rare skill is in the translation and design. However, as long as she's capable of reliably communicating her vision and design to a decent seamstress she could easily offload the actual creation to others. She could focus on meeting with clients, translating their design and communicating to the people who will actually put it together.
If she wanted to go in a little further, she could work on apprenticing a few designers as well. She could still sit in on most or all meetings with clients, communicate broad ideas to the designer, check their design before it gets sent to production, etc.
Basically I think her company could scale just as well as any decent IT consulting firm (or really more appropriately any advertising agency) might.