Not sure if you were referring to the specific news in this post or in general - but for people who aren't aware he did write his own game with it's own system
Phoenix Dawn Command
Haven't had a chance to play it, but I've been intrigued by the concept - PCs are people that have have died are returned to life - they can increase in power after additional deaths, but know they can only return a fixed number of times so there's tension of whether now is a time worth sacrificing. Also interesting to see as an alternative card based RPG.
I remember reading comments from Keith that part of the motivation of making Phoenix was to have a creative outlet independent of WOTC/Eberron back before DMs guild was an option. So it would be interesting to see if he goes back to do more with it again.
As for Threshold - I've been interested to see what comes of that project since I heard about it. It would actually fit nicely into my homebrew setting so if he ends up developing it more independent of Eberron it actually might be more useful to me as much as I otherwise love seeing Eberron get expanded.