With drive following in their footsteps a catastrophe really could have ensued - drive was at that point (I believe? It was a long time ago) already being marketed as good for organizations - any organization stuck with IE6 for stupid corporate reasons may have decided the potential for the site to suddenly stop working was too risky and immediately started migrating to a competitor that offered long term support.

I think a difficulty seeing a catastrophic is because YouTube is not valuable to businesses[1] and when your income source is more distributed (no large contracts) there are less chances to really shoot yourself in the foot. You have to piss off all your customers in a way that - really - you should probably see coming.

[1] I don't mean to deride the service, but it didn't have any commercial tie ins at this point worth mentioning, stuff like professional streamers and hosted partnerships with IP holders came later, at this point they were interesting in pop-culture but not a tool for making money.