On the other hand, editing vector graphics has no intrinsic need to be hosted. Just because a cloud-based FOSS desktop in the future could be imagined doesn't make it a reasonable idea. What would be the point, other than massively increasing complexity and points of failure in terms of reliability and security?
Snarkiness aside, being able to "deploy a single version of software" is itself incompatible with the ability to self-host, making it a moot point for FOSS (let alone for FOSS that has no practical reason to be SaaS in the first place).
Sure, but another user might have another version installed. That might be because their package manager is behind the latest release, for example.
Self-hosting means it's still FOSS and you don't need them if you really want to have your own install.
SaaS deployment means it's easier to maintain for the majority who don't care.
The good news for FOSS is that hosting costs just keep getting cheaper, so providing free SaaS is increasingly feasible.
There’s also the “third way” of FOSS with a hosted option available. Wordpress is a good example of that. If deploying such projects on the cloud eventually becomes trivial, then you could imagine a FOSS desktop in the future might have a cloud component (or be entirely remotely hosted). That might sound odd, but consider you still need to buy hardware to run your FOSS on, so renting that hardware instead isn’t a great leap.