In the past, what typically happened when new technology was released, is that the old certifications stay effective for some time. This could last for a few years. Eventually, once everyone moves to the new platform, Microsoft will let the old certification
holders know that upgrade must be achieved otherwise you give up your certification status.
Also typically there may be an upgrade path from the old certification to the new one. For example, with Windows NT to Windows 2000, MS provided a test that you can take to upgrade the certification. This is also the same with 2000 to 2003. However if there
are new requirements for the new certification that didn't exist in the old one, you will be required to take the new test too.
The bad news with the upgrade path is that typically developers don't get an upgrade . For example, from VB6 to .NET, you will need to retake all the tests. Elective exams may still apply, but typically the core exams must be retaken.