I think that besides Figma, it would be great if there were good FOSS alternatives to Miro and Mural. As for design-oriented collaboration platform that go beyond the shared canvas to include other design tools and processes, I think the future looks bright (esp. on the FOSS side of things). There’s a lot of research in the area of decentralized (federated, peer-to-peer) collaboration with offline support and sync (e.g. in the field of CRDT’s). Many low-level components and libraries are being built that will allow great applications to be built on top of them.
PS. In follow-up to my Fediverse advocacy post just now: Penpot is on the fediverse too: @penpot@fosstodon.org.