Honestly I have to be optimistic and say a 70% chance. Simply because if you look at sales of L.A Noire they are really good compared to some other franchises that Rockstar owns. I think the new game would have none of the staff from the original and many changes will probably be made. To be honest I wouldn't expect much revolutionary in a sequel its creation would be a cash grab an attempt to capitalize on the originals success.
But Rockstar is known for creating actual franchises out of their IP. Look at Midnight Club and GTA or even the less successful ManHunt. If Rockstar sees L.A Noire as the next big franchise which they might then expect them to create a sequel. However a sequel will likely take time Rockstar doesn't usually just churn out sequels.
But I fully expect Rockstar to consider L.A Noire as a franchise and the possibility of a sequel is very strong. Of course we will likely Red Dead Redeption 2 come before sequel to L.A Noire!
-JC7
"In God We Trust - In Games We Play " - Joel Reimer
