When it was requested to allow extensions for structural types, such as tuples, one of the arguments for not doing it right now was that it would require variadic generics to do properly and Swift doesn't want to implement a half-baked mechanism that will need to be replaced later. Even though in practice, the length of tuples that people are going to use very probably has some reasonable upper bound (who's going to use 50-element tuples?).
Now we're talking about a feature where, without variadic generics, you can only put up to 10 items inside a view body—something that is a very real limitation in practice—but the feature is merged anyway. Yes, maybe variadic generics will happen until the release. It's more likely that they are not though, and then nobody is going to rip the feature back out again.
I find this to be weirdly inconsistent and it's one of the reasons why I wrote in the other thread that it doesn't look as if the Swift Core team cares about the fundamental issues with Swift as much as about flashy new features that can be marketed well.