There has been no news of a School Rumble season 4. As you've mentioned, the series ended a while ago and usually an announcement would have been made by now. So, there probably won't be a new season for School Rumble.
If you like School Rumble you'd probably enjoy:
~Ouran High School Host Club
My manga lists: Wish List
, Reading List
, Complete List
It appears you didn't get the memo that every upcoming season is the worst season ever in the history of anime.
Fandom is 95% waiting and 5% mindblowing epicness.