My TLDR response here would be this: Vimeo isn't Evernote and people are paying a lot more to expect more. The nature of this means that smaller bits of "product rot" will push them away faster than what a consumer would tolerate. These are already people who needed to deliberately avoid Youtube, so they aren't afraid to migrate again if needed.
There's also a lot more competition with Vimeo than there is with YouTube. So options exist to find.
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But I'll break down my thoughts further. I'm familiar with the scene (a lot of artists use Vimeo for their portfolios, as well as working with clients on NDA content), but not intimate. So I'd love someone for me to call me out here. But:
There's 2 lenses here. Your lens implies Vimeo is the best service in this niche space, that reducing down the staff count to a skeleton crew will keep it as the most competitive option, and that as long as this isn't disrupted that it'll be business as usual. And we'll be charitable and assume this doesn't enshittify. Those are all valid points. I'm much less charitable, but I can still work in this lens for the sake of argument.
The lens I'm looking in is more at the type of person using Vimeo, not the type of business Vimeo runs. Compare this to Evernote. It's a lot closer to Twitter or Facebook, where remaining users will use it simply because "it's familiar" more than for any competitive edge. It has everything you need, and even if costs rise, we're still talking about one lunch outing per month. It's a "sticky" product benefiting from previous goodwill and marketing.
The people on Vimeo aren't "sticky". They are closer to the type of person who leaves Windows for Linux because Microsoft keeps pissing then off. In fact it's more like they are Linux users who jump around from distro to distro because they already forsook the market leader. They are "actively" on the move and aware of the tools they use. Given that Vimeo is a highly premium service when you use Enterprise, you need to be active. You don't want to be on a sinking ship and have your work crash with it.
So I see two roads here. Some users will stay "stuck" because maybe nothing else does compared to Vimeo. Or because some larger pipeline relies on Vimeo and it's beyond their control. Then some users will be either leaving to another service, or actively keeping an eye out for competitors in the near future. That's what I see as "different" here.
Now, taking my charitable lens off: I do think there will be a lot of small issues pushing people off, and then a few huge ones. Small things like site performance degrading as they scale back server, and worse support as they slash labor. Then the larger things will truly push people, like a price hike, change in monetization models, or failing to honor any deals made pre-bending spoons. Or even a huge data leak. Those things, big and little, break the foundation of a trusted business.