Brits resident in the EU post Brexit to be given extra free movement rights

Politico.EU - Brits resident in the EU post Brexit to be given extra free movement rights

Essentially, there was an earlier expectation that British citizens who move to the EU before 31st December 2020 would be land-locked within the EU member-state that they were resident in on 31st December 2020; i.e. their right of residence would be limited to that member-state as they are longer be EU citizens.

However, 25 out of the 27 EU member-states seem to have agreed to relax this requirement and will allow British citizens who move to another EU member-state to accrue permanent residence by five years continuous residence across EU member-states.

This is likely a huge increase in rights of British citizens and perhaps even of evolution of freedom of movement within the EU as so far, one had to prove five years of continuous residence in a specific member-state to acquire PR in that member-state.

This is a developing story and it would be interesting to see if
(a) this is extended to nationals and family members of other EU member-states as well,
(b) this is implemented by national legislation rather than by EU law (as 25 member-states seem to have decided this rather than the EU itself),
(c) what happens to those resident in the other two (unnnamed) member-states and
(d) whether it applies to the non-EU EEA member-states.