I want to make sure about Discontinuation of MCAD,if so when?
Once you are certified as an MCAD and/or MCSD, you are always an MCAD and/or MCSD. The certification will not be discontinued. As for the exams themselves, Microsoft gives a one year's notice before discontinuing any exams. They have not done this for the MCAD exams yet. Keep watching http://www.microsoft.com/learning/mcpexams/status/examstoretire.mspx to see when your favorite exam gets discontinued! Still, I would recommend that you take the required exams first: (70-310 or 70-320) and (70-305 or 70-306 or 70-315 or 70-316). That way, if the exams are discontinued any time soon [remember, it will be at least one year], you can still take 70-431 as your elective. Since this is a newer exam, it has to stay valid for at least two years before discontinuing, but chances are it will last much longer. Best wishes in your certification studies.