On github under "32 Bit App warning on High Sierra", @tedchoward commented on Apr 26, 2018:
Yeah, the main problem here is that the Frontier kernel uses a lot of Carbon APIs, which are not available for 64-bit builds.
[and later:]
The warning is for future release of macOS. The writing is on the wall.
On Sunday, April 29, 2018 at 10:44:05 AM UTC-6, Dave Winer wrote:
That means if you [...] are looking for something and can't find it, this is a good place to ask for help.
I'm looking for hope. I started using Frontier in 1992, and I'm still running Frontier 10.1a15 under Mac OS X 10.7 Lion in VMware Fusion. I could maybe move forward a few more versions of macOS, but Is there any chance that Frontier will ever be rewritten for the future (e.g., Catalina)?