I was going to make this post, except I'm not really tired of Fate.
THE MASTER PLAN:
1. Convince Nasu's friends to stop writing Fate and write Tsukihime instead.
3. Have Nasu freak out, take over and rewrite it all.
4. ????
5. PROFIT!
TBH, I thought Narita was at least partially baiting Nasu to return to Tsukihime with FSF.
More seriously, if/when Nasu's clique gets tired of writing Fate, we'll see different stuff.
GO could very well be a "go out with a bang" conclusion for Fate (man, explosion endings are the worst!)