When does the PMBOK current version subject to change?

 Hi all,

          First of all a humongous thanks to the admin for all the efforts to have the site so lively and useful to PMP aspirants. My question is that, when does the current version (4) of PMBOK likely to change?

Also, I am preparing on the current version, when is the worst case before which I should ought to complete? 

Thanks in advance,

Regards,

Balaji Rajendran.