I myself am strictly a singleplayer guy, wish I had time to actually make missions, or make them reasonably and not shove them full of massively complex scripting.
Or play the game, been probably a year since I last actually played it instead of just modding.
I'm sure there are SP people left, they're of course the minority nowadays.
There's a guy Undeceived who has made a few good SP campaigns in recent history.
And you can always make your campaign playable in co-op to peak the MP peep's interest too
Not sure if this thread should in some mission depot forum but I don't really care anymore because of the lack of traffic here nowadays