In order to break this "critical mass" of activity, I suggest dividing the game into three (simplified) sub-nomics, and have them each develop as their own Province.
There has been precedence of Agora having a similar "divide" (the Blots and such), although this would be making the slices in a different way. Perhaps it helps. (Also, this is personal interest, but I would love to see differences in 'axiomatic' perspectives in each one and see how each mini-Agora develops.) This is also inspired in the BLO vs GNO vs MIC dynasty of Blognomic: https://wiki.blognomic.com/index.php?title=The_Fourth_Metadynasty which seemed to be one of the more interesting ones, and we have the amount of players to make it work. This definitely qualifies for "radical" ideal though, and as ais has pointed out, may not work. But I figure it would be good to put this out anyway, for consideration.