Definitely, but it will take a couple of months to a year until an OS/Java update makes it unusable. Even if not, you're stuck with a dead, legacy system. In the case of JetBrains, and other offline solutions, companies (i.e my company) can't ask anyone for support anymore. And with every passing day the world moves on and we're stuck on a dead platform. So maybe we won't update that same day, but we would in a couple of months maximum.
My point is, it's really how you handle it. For example, codebender can stop developing stuff and stay alive for months with minimum cost. Even better, I can notify my users in advance, disable registrations, and keep the site running for a year with my personal budget.
Doesn't that disrupt you less than, say, IntelliJ shutting down one day and in a few months their IDE is so stale you can't use it? (I'm using IntelliJ here because we're using PHPStorm to develop codebender so I have personal experience with it)
And honestly, that goes the same for everything. If Microchip goes down, you can still use the 10 processors you have lying around, but they're essentially worthless to you because you have to switch to a new processor, one that you can base your product on. Same for your computer vendor, you can still use your computer but you might as well throw it away because there's noone supporting it, and it's going to have open, known security issues soon, so the faster you throw it away the better. Yes, this issue is more enhanced with subscription-based models, but that depends a lot on their handling of their situation, and -my point here is- it's more of a theoretical & psychological threat than a real one.
Of course, you don't have to agree with me, and of course, I'm biased, for obvious reasons