That source code isn’t worth much without the underlying domain knowledge, large parts of which only exist in the employees’ heads, more often than not. Maybe if the code is really, really well documented. ;)

Companies could in principle train an in-house AI with their corporate knowledge, and will likely be tempted to do so in the future. But that also creates a big risk, because whoever manages to get their hand on a copy of that model (a single file) will instantly have unrestrained access to that valuable knowledge. It will be interesting to see what mechanisms are found to mitigate that risk.