The PNC better not count on Indo support in 2020 and should instead come up with some gerrymandered parliamentary districts.
And with a smaller Indo vote by 2020 you are still so sure that they hold all the cards.
The PPP will need to be very worried about its own failures to win non Indo support.
1. Unless the coalition is amazingly stupid they will lavish the interior with benefits and will win significant Amerindian support. The PPP will not be able to lavish patronage, so will lose some of the support which it has.
2. The mixed vote will be larger. They aren't inclined to vote PPP, and if the mixed/black component of the AFC remain happy with Granger, the coalition will continue to get their support.
Its really up to APNU whether they win or lose in 2020. If their programs benefit the country and corruption is curbed they are well positioned. Especially with Jagdeo leading the PPP. Videos of his racist rants will ensure his demise and he will regret the thinking that an Indo vote and an Indo vote only guarantees victory.
By 2020 the African/mixed vote will quite likely reach 50% as all of those mixed people born after 1991 come of age.