Apple updates it's image converter separate from Aperture, it is updated, there's a K-1 profile. Tess just bought a new iMac 4k, and ported Aperture over, it still works great. I'm importing K-1 files every day without issue. Just be sure you have the latest OS upgrade installed. Camera importer updates come with the OS upgrades. If you don't have the latest Apple upgrade, (free) you may not have the K-1 profile.
Apple may not be supporting Aperture, but they have not broken it by making i incompatible with current OS upgrades either.
It is what it is, it's just not getting any better, where as Lightroom and other software has.
It's still miles ahead of any other Apple solution, and I hate , despise and loathe Adobe.
All three of those things.... honest.
If you consider I paid $79 for this version of Aperture, and I've sued it 6 years now, it's one of my best purchases ever, like less than $20 per year... an it just keeps on going. It's like cocaine...
"They say cocaine is for horses, not for men
They say it will kill me but they won't say when"
They say Aperture will die, but they won't say when.