Not wanting to sound like a flame, but honest question... why do you not think that OS 4 is the link between the original Amigas and the Next Gen Amigas? AmigaOS 4 is still AmigaOS at its heart - that's a pretty big link!
Not a problem. NB my reasons are only personal to me though and might not make sense to others so I hope nobody takes offence. It's just a feeling I have now compared to how I felt using machines 3 decades ago.
It's not that there is no link at all between an Amiga 4000/040 from Commodore and AmigaONE x1000 and other Next Gen Amigas in my opinion, theres is a spiritual link back to the OS ethos in Workbench/Kickstart for sure. They don't look like either OSX or Windows design choices either that's for sure. It's just for me the Commodore Amiga's were more than just their OS. They were from a different time where your host hardware took the brunt of the workload through well thought out exclusive custom chipsets to make the use of the machine more pleasurable whereas the newer machines are all 100% software type solutions. Sign of the times and I am not passing negative judgement on the new machines though (it's not like you will get a virus as often as even a Linux based machine haha and for some people that is worth every single dollar invested in any Amiga system).
In a way for me it feels like computers have come full circle back to the original Commodore PET in 76? (arguably the worlds first 'modern' mass produced commercial public targeting computer) which just had some nice features built into the system comprising hardware for sale to any company...like for example the very useful PETSCII graphics set for making simple games (look out for PET Moon Patrol one day haha)
After a couple of decades of ingenious custom/bespoke components from all manufacturers we are back to the very early times. Maybe one day someone will write an OS specifically for Oculus Rift to make a radical new path for domestic computers but for now we are back in the 'quality computer=quality software/firmware included in the package running on generic components'.
But even if all you do is run WinUAE you're still an Amigan, which is why semantics like emulator users, Commodore Amiga collectors and NG Amiga owners today are part of the same group. But hey I still only have CRT TVs in the house but watch HD movies on them just to be awkward*

(well technically I am just feeding a broadcast quality signal into the TVs to approximate the quality of analogue TV transmissions which at the time were far superior to the non-HD options for TV set top boxes today btw so not crazy at all IMO)