stored procedure variable names

In all other DBMS, the variable names have a distinctive character to
differentiate between variables and column names:

Example:
SQL Server uses @
MySql uses ?
Oracle uses :
Firebirdsql uses :

It makes it easier to write and manage queries especially in stored
procedures.

Just compare the below:
create stored procedure get_user_for_editing(user_id int, out username
varchar)
begin
select username into @username from users where user_id = @user_id;
end;

to this mess:

create stored procedure get_user_for_editing(user_id int, out username
varchar)
begin
select u.username into get_user_for_editing.username from users u where
get_user_for_editing.user_id = get_user_for_editing.user_id;
end;

Prefixing the variables (ex: p_user_id) makes the application code harder
to write as we have a lot of dynamic code that is expecting "user_id"
instead of "p_user_id".

Is there any plan to add a character to differentiate between variables?