Well, FCA's CEO recently confirmed that in their 2020 plans they are calculating with 60% of the Co2 penalties being "recovered" via sales of their own EVs, the remaining 40% through the Tesla pooling agreement.
I think that 60% is probably optimistic, because it relies on Fiat selling compliance EVs at good prices, but even with only 40% of their penalties reduced via Tesla that's a significant source of income.
It was clear from FCA CEO's statement that they are going to use Tesla to reduce the Co2 penalties to zero - they just don't know how many Fiat EVs they'll be able to sell in 2020 and 2021.
With PSA on board the effective ZEV credits required to zero out the penalties quadruples - but maybe the increase is even higher, as PSA doesn't really have a chance to cover 60% of their penalties via their own EVs.