Only the Apache-licensed version is dead. The commercial arm (Element) forked it and relicensed it under the AGPL to make sure nobody but them can use their post-fork changes commercially. (Element demands you sign a CLA to contribute. Don’t[1].)
I mean, for years Dendrite was positioned, by the developers of Synapse themselves, to become Synapse's successor, and Dendrite was getting a ton of funding and attention to make sure it happens.
It didn't then, and now that the situation is dire for Dendrite (with no funding and no official effort being put into it), I have little hope things are going to improve.
