IMO there are always going to be tensions (as well as differing personal preferences) for surface syntax and authoring environment.
What I think may emerge though is a better shared understanding of “what’s needed” as well as a great (ideally libre) library for implementing those ingredients consistently and interoperably — e.g., a DOM/CSSOM for these graphs as well as maybe an adaptagrams- or cairo-like library for the common layout and drawing capabilities.
(For example, have you noticed how many general-purpose drawing tools now have “align and distribute” capabilities that all work similarly? AIUI, many of those tools are either directly using or are inspired by Kim Marriot, PJ Stuckey, Tim Dwyer, & colleagues’ work in this area?)
It leaves me wondering: if somebody carefully looked at all the languages and all the use cases, is it possible to build a single language that does it all while still being easy for smaller charts? Or are the goals of easy and complete in too much tension, such that we're better off with a bunch of languages, each one tuned for making things easy in a particular zone of the problem space?