Don't worry, boys.
As a Brazilian following close this matter, this track has zero chance to even be built.
This news was just a politics move to change press focus.
The F1 itself didn't know about this either before this announcement.
Interlagos has a signed contract until 2020 chancelled by F1 and São Paulo city hall, so the 2020 Brazilian GP will be there.
About this Rio track, only the area exists. It was conceeded by the Brazilian Army, after 5 years of cleansing (there was thousands of explosive materials scattered through the landfill, now they say it's safe... wow)
There's not even contractors hired to built this, only a proposal project created by Tilke company.
There is NO WAY of this being built in 7 months, in order to host any race next year.
Maybe (a BIG maybe) something can be done for trying to host 2021 onwards, IF Interlagos don't renew their contrats with F1 first.