This is problematic since, for example, Chrome 64-bit isn't yet the default release build.
Surprisingly enough, there isn't even an official supported build of Firefox 64-bit for Windows. Coupled with the Chrome issue you mentioned, I'll bet that at least 80% of users out there aren't using a 64-bit browser.
This is insane in 2015. I understand the difficulties of porting, but at the same time, I've had a 64-bit CPU since 2009 and I was late to the party :)
Surprisingly enough, there isn't even an official supported build of Firefox 64-bit for Windows. Coupled with the Chrome issue you mentioned, I'll bet that at least 80% of users out there aren't using a 64-bit browser.