There’s a physical limit to everything (I’m talking more land space here), especially since a site like youtube will only get more expensive to run as time goes. I expect them to start deleting content that doesn’t make them money like videos with under 5 views that are over a year old relatively soon especially with the current economy. This would make sense for them and would free up a lot of their storage. Google doesn’t disclose the profit margins of youtube but I am pretty sure they are not very large especially now with 8K HDR videos being available