The 3 halls are roughly 2 ha (1 ha = 10.000 m²), a hotel does not take that much space and sure, if they count 46 ha "biologically active surface" (which appears to me like they have to do so to compensate for the parks environmental impact) it is more realistic, but even 100ha is an insane area.
However, if we consider every area associated with the park, 200ha (including 46.6 compensation area) is not that unrealistic. As of now, the theme park (and only the theme park) covers an area of roughly 40has (give or take 10%, I checked with 3 different satellite images). Including adjescent areas + the second parking lot, we make it to a total of 52ha. Adding the 47 compensation area, we are already half way there. The Western Camp is another 5ha, which I did not include in this calculation.
Talking about possible additions, apart from the Tilt-Coaster, I can really see a STC making its way to the park, and maybe they will go for the Giga. I'd also love to see a big scale Freefalltower from Intamin being build. Not quite sure if a "classic" tower, or a Sky jump... or just both. But a good, intense freefall is something the park still lacks.