Is it necessary to get a masters degree for industry jobs in Machine Learning or AI?
It depends, I think, on what sort of job you want. For people in the trenches, even at IBM/Watson, an undergraduate degree is probably enough to get hired. You would likely be a team member building things at the direction of a manager. Creativity would be in the "how to do this" rather than in the "what do we need to build" area. 

However, at the level of doing research at IBM, and I assume others, the requirements look a lot like they would for an academic position. Lots of the people there have doctorates, actually. I don't know that a PhD is necessary to get hired, but the more education you have, the better your chances. 

I know people at both these sorts of levels at IBM and at Oracle. 

It used to be that at IBM the trench types could get a doctorate paid for at the company, but that option has disappeared for a while now. They might be a bit flexible about giving you some time-slack to do it, depending on the manager, but funding is unlikely. 

At smaller companies and especially at startups it is probably much more flexible, but also risky. I also know people doing interesting things at such small software shops who have a more basic formal education though they are good at learning on their own and staying at the forefront.