Effect of disabled user id on system.

hi guys

I have replaced one guy in my current project.

I have got my new user id ,So Basis wants to disable old guys user id .

Now my concern is , what will happen to any batch job  or process chain scheduled periodically with the old user id .

will it run as usual or it will not ? I will have to reschedule all of it with my ID ?

Gurus , Please suggest ASAP as it needs to be done at earliest .

Thanks in advance.