Since there has been more transfers taken place after the patch was released, will there be any chance of another update?
If not, in future Football Manager games, can the last patch be released after the March transfer window has finished?
The transfer window shuts in January for English sides. However npower sides and non-league sides can sign emergency loan players. SI don't include these or short-term loans(anything shorter than 6 months).
Other transfer windows for other sides may be still open but SI have a data lock which means no information after a certain date can be entered. This gives them time to test the game etc.
There are unofficial databases in the Editors Hideaway which could be what you want though .