I haven't really been following that closely... I think in the US some (a very limited number) of on-set VFX artists have unionised, but in practice those aren't the people doing the majority of the post-production VFX at ILM, DNeg, Framestore, MPC, Weta, etc...

One of the complications is many of the VFX facilities have offices in many different countries, and in the past have been chaising subsidies (Canada was a strong location 10 years ago or so), and different locations have different laws as to what's possible.

i.e. in London, overtime wasn't generally paid (but artists often still had to do it), although I believe DNeg London started paying it more recently (not in India though), and I seem to remember people saying Vancouver didn't generally pay overtime, but Montreal did but I don't know how accurate that is more recently...

Can't the former Weta employees (both laid off and otherwise) splinter off from Unity into their own VFX spin-off? Surely they have enough industry contacts and street cred so that getting projects wouldn't be a problem.