Modding support is a good idea.
The game is still selling on gog or steam so you are getting funds that can be spend working on it.
Or if you lost any hope and interest - make Harbinger open source so the community will create its own tools.
Or start another kickstarter to fund modding support.
There is always a way if you want it to happen and have some good will.
Take note that many relatively new and nice games are already dead because community complains that devs don't give a damn anymore.
Such comments on steam are instant turn off for buyers.
On the other hand take a look at FTL, its mods and huge replay value.
