In most cases, there will be no issues with changing the field name. But look out for any indirect references to the field by name that put the field's name in quotes.
Example: GetField ( "Table::ForeignKey" )
Since changing the name won't automatically update the name in this quoted string, this funciton call will fail if you don't find and update it after changing the field name.
ExecuteSQL, GetField, Set Field By Name, and Script Parameters are the most likely culprits to look for if you think there are any in your system for the field in question.