This might be the end of playing DOS games on a Mac (without VirtualBox or some other excessively bloated workaround).

1. What (if anything) will Gog be doing with their Mac versions of DOS games?
2. What DOS games should I make time for before it’s too late?

DOSBox is an emulator, so developers just need some time to modify the codes.
DOSBox have run on various CPUs.
64-bit-only on x86-64 will not be a big problem.

Get a PC already :-P

I've been using 64-bit dosbox on Linux for years. One thing to be careful of, though, is the patches. The only patches I trust are the munt and glide patches. In particular, the popular Daum patch was badly broken last time I checked, and probably hasn't improved since.

Thank you, Qbix and everybody else working on this. So there will be some sort of solution, though — unless Boxer gets updated as well — Gog will have to find a new way to package the games. Granted, a simple zip file would do the trick in a pinch.

I thought Apple's plans were to more or less remove gaming from OSX as not something befitting the Apple users. Games are for losers. Winners have no time for them.

OK, calm down before you send a death threat to me. I think Apple is doing a huge mistake. Thankfully one can multi-boot with other operating systems that are more gaming friendly. DOSBox is also not made by Apple.

Might consider bochs....

It is a real concern. I E-mailed GOG and got a response from Genoan I think. Here's what he said to me.

"
Genoan (GOG.com)
May 18, 10:21 CEST

Hello

Our Product Team is aware of this issue and are working to make our releases compatible. I can't promise that all games will be updated. Some releases are maintained by their Developers and making those compatible is not something GOG can do.
As for the DOS games I'm unable to comment on the technical aspects or who we are in contact with.
Sorry for the inconvenience.
Regards
Genoan
GOG.com Support".

I will not be upgrading my iMac to Mohave until I am assured that my games will continue to work once 32 bit support is removed. Alternatively, I'll ditch the iMac and get a Windows 10 PC. I've been a Mac user for 7 and a half years now and I like it a great deal, I really do, but, it's undeniable that far more games exist for Windows than they do for Mac OS. I want to play games like Jazz Jackrabbit 2 and Descent 3 and Return To Castle Wolfenstein, they don't exist on the Mac at this time. I hope the games are updated to make them 64 bit compatible, but the problem is neither Boxer nor DOSBox have been upgraded in several years now. I'm not sure if anyone's been working on a derivative of Boxer or not.

Just using dual booting would be less expensive ;)

On topic:
I don't really think that emulated games will be a problem in the long run, maybe not even Wine-wrapped ones, I guess development will catch on after a while. And if not there is always dual booting, using virtualisation, or potential new emulators... id say there is less hope for actual Mac versions that are 32bit, those won't run anymore but I don't see developers spending much money on getting them updated, fortunately we always get all versions of games here.

Not sure how many games will even be affected, I don't remember a whole lot that are still 32bit in my library. The only program were I got the "will soon be outdated" warning so far is the Steam client :D

As far as I can remember, once I upgraded I think to Mac OS 10.13.2 or .3, the first time I ran my DOS games after installing the update I got that warning message for each game. Most of the games I've bought from GOG use Boxer in order to run, those that don't use either DOSBox, (The Jungle Book), or SCUMMVM, (Beneath A Steel Sky, Flight Of The Amazon Queen, Leisure Suit Larry, Lure Of The Temptress and so on). I don't recall seeing any warning message about Steam not working in the next major Mac OS update when I opened the Steam client, but considering how frequently Steam publish updates to their client, I won't be too surprised if they address this issue. Tonight I installed The Jungle Book on my MacBook Air which I think is still running Mac OS 10.13.4, and I didn't get that warning message when I first ran the game after installing it. Certainly dual booting is an option, and I know you can run Windows 10 on the Mac, I'm just not sure I want to.

Rather similar to previous times Apple have done a great change - first replacing the entire OS (Mac OS 9 to the UNIX-based Mac OS X), and keeping applications from the old ones running for a while in a legacy (Classic) mode, later the switch to x86 and emulating PowerPC for a while. Now, 32-bit support have gone through its "legacy-mode" phase and is being removed altogether.

This is the reason as to why the Mac release of old games here are based on Windows or DOS releases rather than old Macintosh ones. We'll be seeing games that currently have macOS-native releases switch to Windows-based ones under Wine and emulation as they're easier to keep running.

Or you could use Parallels and install Windows through that and then you can have your 32 Bit legacy stuff work. If you have a valid copy of Windows.

Crossover actually runs DOSBOX under emulated windows at full speed for pretty much all old school DOS games.

They are committed to 64bit support and have already started porting it.

For GOG games, you just download the windows installer under extras on your Mac and execute it as a setup program for CrossOver. It is really easy. You lose GOG Galaxy compatibility but can run almost anything.

I remember trying to play Rise Of The Triad in mid 2012 using CrossOver Games, let's just say it didn't go well. The game started and ran, there was sound, but no visuals, at all, just a flashing garbled screen.