The problems with that feed which he touched on in the video are pretty significant. If you subscribe to channels that put out lots of content and ones that rarely do, it becomes much harder to use.
One thing he didn't mention is also that it's not conducive to discovering and gradually catching up on the back catalogue of a new channel, which is something the home feed excels at.
I'm sure YouTube prefers you use the home feed and has no plans to improve subscriptions, and there are real issues with it, so it'll probably continue to decline.
That's a fair point, improving the subscription feed would be in their best interest for the people who use it, even if that number is low.