I am curious about this as well. I think the difference between machine learning and software engineering is that companies may only need a few dozen machine learning engineers. They may need thousands of software engineers. There may be increasing demand, but the demand will never reach the demand of software engineering. Except at the premium ultra competitive level, where a data scientist who is globally known can…
Soon, however, one could argue that 'traditional companies' will no longer be the norm - data science, ML, etc. will play such a crucial role in the majority of tech firms that the number of companies using it will rise. That's when I expect we'll see a huge portion of software engineers knowing ML concepts. Alternatively, I wonder if we might see the rise of smaller companies contracting out all of their ML to larger ones.
I would also be curious to know if ML background helps one to get a job at a place like Amazon/Google for even 'traditional' positions right now. The amount of data they have now must drive demand for engineers who can write software that takes advantage of it, regardless of position. Of course, like you said, they'll always require engineers to fill more traditional roles with no data interaction.