I expect it to work exactly how swimming did in Island living. Most existing worlds just don't have the areas for it with it in mind (base game worlds don't have oceans esp, therefore it couldn't be considered a base game update- it'd actually be updating GT,C&D because the other worlds don't have a beach area to access the deep water without adding the new ladder to the fish area,) and to get it, they'd have to spend time messing about with it. Newer worlds are being built with this in mind, though, Brietchester has a swimmable lake, and Mt. Komorebi has a swimmable river. They might add hiking trails to new worlds, maybe they could give OR some polish by making the hiking paths functional in the Deep Woods area of Granite Falls? Skiing, Snowboarding, and rock climbing though? Locked to the map.
I do think its a bit unfair, though, this isn't exactly something that the sims team can win with. If they add it to other, new packs, they'd be accused of recycling content. I doubt that the slopes exists necessarily as a debug option that could be functional.
