A helpful French goon has done a quick sketch of the location for the new cred:
http://www.disneycentralplaza.com/t53982p475-france-parc-asterix-paris-1989#3442290
The second image denotes a playground, eatery and a potential other new attraction, rumoured to be for 2023 (rather than opening with the coaster)...
The pathway to the coaster actually already exists as staff access... Apparently a waterfall (cascades) will be added either to or from the existing pond/lake (the Grand Splatch one)...
Finally, apparently they want a new hotel (never stayed in the one they have atm, looks nice though), and here's some concept art to drool over:
EDIT - Further reading seems that they're getting a new 4D cinema next season (no idea where, presumably in the Victorian indoor section is my guess) and seemingly the utterly fantastic stunt show has finished for good... Which upsets me greatly because it was one of the best shows I've seen at a park, especially the finale ❤️ Hopefully it'll be replaced adequately...