Darmstadt - Mathildenhöhe
https://www.hessen.de//presse/pressemitteilung/kuenstlerkolonie-mathildenhoehe-auf-of fizieller-vorschlagsliste-fuer-unesc-0

Possibly Iles Marquises (French Polynesia) or 2020
http://www.tahiti-infos.com/UNESCO-les-Marquises-ont-un-fort-potentiel-pour-devenir-p atrimoine-mondial_a130807.html

Nimes (France)
http://www.objectifgard.com/2015/06/18/unesco-nimes-lambitieuse-candidate/

Chinese Altai (China)
Incomplete in 2015. All slots for 2016, 2017 and 2018 already taken.

Darmstadt is for 2020. Augsburg is the German nomination for 2019.
http://presse-augsburg.de/presse/jetzt-ist-es-offiziell-augsburgs-antrag-fuer-das-une sco-welterbe-wird-2018-nominiert/

http://culture.workercn.cn/75/201504/30/150430072620012.shtml

According to this report (in Chinese) there have been discussions between China, Mongolia, Kazakhstan and Russia on a possible extension of the Altai WHS which I assume will cover the mountains in all 4 countries. The plan then is to create a bigger mixed site which will not only include the inscribed Russian site but also the Mongolian petroglyph site.

Maybe there will be a delay because of this although the report does not say when a nomination will be made.

Gaya Tumuli: Gimhae & Jisan-dong

Aiming for 2019. Interesting how Korea continues to merge two tentative nominations into one.

http://www.ajunews.com/view/20151020114125109

Plantations of Caracao (Netherlands)
http://curacaochronicle.com/local/old-plantations-in-curacao-may-become-world-heritag e/

Probably one or two of these Chinese sites:

Candidates for 2019

Nieuwe Hollandse Waterlinie [Extension] (Netherlands)
Iles Marquises (France)
Gaya Tumuli: Gimhae & Jisan-dong (Korea)
Pombaline 'Baixa' or Downtown of Lisbon (Portugal)

Curacao will be a year later.
The Dutch nominations (as indicated by letter to the Parliament in May 2015) are:

2017 nom, 2018 inscr
De Koloniën van Weldadigheid ( Veenhuizen, Frederiksoord en Ommerschans), samen met de Vlaamse koloniën Wortel en Merksplas.
2018 nom, 2019 inscr
De Nieuwe Hollandse Waterlinie, als uitbreiding van Werelderfgoed Stelling van Amsterdam
2019 nom, 2020 inscr
De Plantages van West-Curaçao
2020 nom, 2021 inscr
De Romeinse Limes, samen met Duitsland en als uitbreiding van het werelderfgoed Frontiers of the Roman Empire

winterkjm, you left out Augsburg (Germany) which is fixed. It is definitely planned for 2019 and not 2018.

Potential 2019 Candidates
Iles Marquises (France)
Hydraulic Engineering and Hydropower, Drinking Water and Decorative Fountains in Augsburg (Germany)
Nieuwe Hollandse Waterlinie - extension of the Stelling van Amsterdam (Netherlands)
Pombaline 'Baixa' or Downtown of Lisbon (Portugal)
Gaya Tumuli: Gimhae & Jisan-dong (Republic of Korea)
L'ensemble monumental de Tirgu Jiu (Romania)
Risco Caido and the sacred mountains of Gran Canaria Cultural Landscape (Spain)