With 10.15, my old and dependable workhorse of a machine - a souped up Mac Pro "Cheesegrater" from 2010, upgraded in every possible way - will have to retire. Catalina, Swift UI, and I suspect most of the ML stuff, now require AVX instructions in the processor, and there is no replacement that I could find that would slot in the socket.
I don't consider it to be "planned obsolescence" or anything of this ilk, given that this computer has been my home office's principal work station - and game station, mostly on Kerbal Space Program - for almost a decade. It will live on as my test Linux server, and I will slot a bunch of cheap video cards in it to run my ML farm, so it will probably see another decade of service.
However, the question of replacement arose. You see, I'm an avid Blender enthusiast, and I often run ML stuff on it, which nowadays means I need a decent video card that I can upgrade. The new Mac Pro would be perfect for that, but it's on the expensive side, given that I mostly use the high end capacity of the cards for personal projects or for self-education.
I settled on a 2018 mac mini with tons of ram and a small 512GB internal drive. The 16TB of disks I had now live in a USB 3.1 external bay, and the video card will reside in a eGPU box. That way, if and when I need to change the mac again, All I have to do is change the mac mini... hopefully.
Since the sound setup is of some importance to me (my bird/JBL setup has been with me forever), and I sometimes need to plug old USB/FireWire stuff, I dusted my Belkin Express Dock, and plugged everything in it.
The thing is, every migration is an opportunity for change. I've been very satisfied with my OmniFocus/Tyme combo for task management, but the thing I've always wanted to do and was never able to due to lack of time was managing my Gitlab issues outside of a web browser. I've been working on a couple of projects this summer, with lots of issues on the board, and I have old issues in old projects that I keep finding by accident.
As far as I can tell, there is no reliable way to sync that kind of stuff in an offline fashion. This trend has been going on for a long time, and color me a fossil, but I don't live on the web. I like having a twitter client that still works offline, I like managing my tasks and timers and whatever offline if I need to, "the web" coming in only as a sync service.
This migration (with its cavalcade of old software refusing to work, or working poorly under new management) will force me to write some software to bridge that gap (again). The web is cool and all, but I need unobtrusive, integrated, and performant tools to do my work. 78 opened tabs with IFTTT/Zapier/... integrations to copy data from one service to another won't cut it.