My guess...
WRC 2018:
M-Sport (probably not Ford backing):
-Elfyn Evans
-Teemu Suninen
-Tidemand/Camilli (DMACK-Maybe they will have with two cars)
Citroen Total Abu Dhabi WRT:
-Sebastien Ogier
-Kris Meeke
-Breen/Loeb/Qassimi (Maybe Lefebvre too)
Toyota GAZOO Racing:
-Jari-Matti Latvala
-Ott Tanak
-Esapekka Lappi
Hyundai Motorsport:
-Thierry Neuville
-Andres Mikkelsen
-Sordo/Paddon (Share third car-maybe have 4 for some events)
OneBet Adapta WRT (if team will have enough money):
-Mads Ostberg
WRC2:
Skoda Motorsport (if they stay in sport):
-Juso Nordgren
-Jan Kopecky
Hyundai HMI Italia:
-Jari Huttunen
PH-Sport (Citroen):
-Stephane Lefebvre (Maybe Breen too)
M-Sport:
-Kalle Rovanperra
-Eric Camilli
Proton, Opel & Volkswagen will probably not competing.