I used to be very enthusiastic about projects like this but AFAICT, decentralized governance ultimately amounts to a contradiction in terms.
Instead, we clearly define the terms under which new folks can join and leave the spec core team, code core team and Guardians in https://github.com/matrix-org/matrix-doc/blob/matthew/msc177... and more formally in https://matrix.org/media/2019-06-10%20-%20Matrix.org%20Found....
So this defines how the wider community can get involved at the top level; and in turn, anyone is welcome and encouraged to submit patches (for implementation) and proposals (for spec) - thus providing a relatively decentralised end result. Our emphasis is more on open governance than decentralised governance for the sake of it.
That said, if Aragon or some similar project came along and convinced us of a better governance model, we’d of course consider it :)