64bit

Mac users

Here's the scoop from Apple, and more details from Wikipedia.

Translation:
10.13 (“High Sierra”, the current OS) still fully supports 32bit
10.14 ("Mojave", sometime this year) will pretty much fully support 32bit. I have tested kJams on 10.14, and found it to work just fine. So even though Apple says “[32 bit] with compromises”, I have found no compromises with kJams.
10.15 (1.5 years from now) will NOT support 32bit

I can now say that it is perfectly OKAY to upgrade to 10.14 when it is released!

FYI: the current 32bit kJams will continue to run and be maintained for the foreseeable future!

In any case, I plan to have 64bit kJams ready to go BEFORE 10.15 is released, so you will have no interruptions! THE SHOW MUST GO ON!

Windows Users

You got nothin' to worry about, I will continue to support 32 bits during and after the 64bit transition.

Sorry for any confusion.