They're probably right, since it's been reported that Google's Waymo has achieved just that - press reports from January say $8,000 per sensor which is positively affordable when compared to $75,000 for a competing sensor.
I think most people think LIDAR is going to eventually be inexpensive -- even Tesla has a few test cars with LIDAR. However, it's a fair weather sensor, so you'll have to do a lot more for level 5.
