Normally, when Microsoft retires a certification exam it’s reached end of life and the technology covered is no longer current. With the 70-534 exam, Microsoft is implementing a significant content update / upgrade to the exam to keep it current with the current state of Azure Architecture. As a result, rather than simply updating the exam content, they have decided to retire the exam December 31, 2017 and replace it with a new exam; the 70-535 exam with the same name.
The 70-535: Architecting Microsoft Azure Solutions certification exam will replace the old 70-534. The core exam content will largely be the same, but the updates / changes are significant enough that a new exam number will help differentiate the difference. This is really a good thing, as it will likely help reduce confusion between the older version of 70-534 and the newer 70-535 content.
Full exam objective details haven’t been announced by Microsoft yet, but the new 70-535: Architecting Microsoft Azure Solutions exam will replace the old 70-534. As a result, it looks like the 70-535 will count towards the the MCSA: Cloud Platform and MCSE: Cloud Platform and Infrastructure certifications. This would mean a direct replacement for the 70-534 as it’s been.