A big part of the market is making CRUD apps. The skills to develop these kinds of apps can be reliably learned. But even still, it's not quite as rote a skill as being a cog on an assembly line. There's still a lot of variability, and lots of parts to master (front end, databases, etc), interpretation of requirements. It's hard to just hire an army of peons and expect them to participate in CRUD.
If the development is exploring out new territory, then the workers will never be a commodity. Making new things never done before. Facial recognition, OCR with high reliability for crumby hand writing, etc. For these workers to be a commodity, you will have to create an AI with human level creativity to do exploratory creation. That will likely not happen in our great great great grand children's lifetimes.