What is the best method for LongTermArchival of a VM

Any 'currently supported' guest OS will be forgotten in 35 years.

Archival is a difficult subject, for such a long period of time, because even if you were to write to Blue Ray, would you have access to a Blue Ray player in 35 years! (which was working, and not in a museum).

Every 7 years at present we have to keep moving archives onto current technology.

So either "print it out" because paper will last for ever, or store on digital storage.

I have ZIP drive attached to wall with a big nail....

Maintaining the  arcive file to the  latest  readable format is expected.  However  will it be deployable  on the future available  hardware and hypervisors is the  question. Preserving the environment  in a vm format  gives you any advantage  over maintaining  physical  hardware?

That is true, virtual hardware does not change.

BUT, with Restore to Bare Metal techniques now commonly and available, that argument, falls down now.

But DR with Virtual Machines is easier.

I am sorry, when I said deployment of VM on newer HW, I mean its for deployment of compatible hypervisor version on which the archived VM should work. The reason for retaining older hypervisor is to retain the same VM version to avoid any incompatibility with the I/O drivers.
Now the real question is will the older hypervisors run on the latest HW or should we retain older HW also to run compatible hypervisors?

All VMware virtual hardware will work, on current VMware platforms.

e.g. we can go to our VMware virtual machine archive in 1998, and use VMs from that era from ESX 1.0, on current VMware vSphere ESXi 6.5.

So there is no need to keep the hypervisor software.

Hardly anything ill be relevant in 35 years
https://en.wikipedia.org/wiki/Timeline_of_computing_1980%E2%80%9389#1981
You can run MS-DOS programs (only .COM, not EXE) of time on FreeDOS or DosBOX (assuming at least you ripped image of 8in floppies or copied them to 3in ones), and MDA is stil alive as 80x25 text mode.
You can run sinclair text editor in emulator.
You still can make IPv4 TCP connections
All other options are washed away no matter how carefully you preserved your images/backups.

Although interestingly in the British Library, they "keep" old computers, so they can run and retrieve data.....from old systems....e.g. Apple, Apple II, Atari ST, Commodore PET etc

They certainly have low light scanner for recovering 3500 years old papyrus format media, but for all practical purposes in 20 years all computers becomes archaeology...

According to the kb article 2007240,  compatiblevm hw ver  list stops with  vm ver 4.0 for esxi 6.0! Is there a  reference to vmware  doc that vm ver 1 can run on esx 6.x?

I fully  agree with you. We archive  vm and hope that they stay compatible for the  foreseeable future.