The latest AMD Radeon driver release seems to suggest the company is preparing to phase out support for 32-bit operating systems. It's hard to imagine anyone running a modern video card using a 32-bit operating system so it's not really a surprise that AMD is taking this step.
The 32-bit version of Radeon Software 16.3.2 can still be downloaded but is no longer as easy to find as users get redirected to a knowledge-base article with the following statement:
A system running Microsoft Windows 10 64 Bit can take full advantage of the advanced visual and performance features of these graphics cards. However, AMD also provides 64 Bit drivers for Microsoft Windows 8.1 and Microsoft Windows 7 to accommodate those users who choose to use an older Microsoft Operating System.
AMD's website also reveals the new dual-GPU Radeon Pro Duo video card will not be getting 32-bit driver support.