I think we should deprecate the partition operator and remove it for v7.

Reasons:

1. Not really an operator: partition isn't really an "operator" in that it returns [Observable<T>, Observable<T>] rather than Observable<T>. This means it doesn't compose via pipe like the others.
2. Easy to replace with filter: partition is easily replaced with the much more widely known filter operator. As partition is effectively the same thing as: const partition = (predicate) => [source.pipe(filter(predicate)), source.pipe(filter((x, i) => !predicate(x, i)))]
3. Rarely used: It's little used, by any code survey I've taken (within thousands of lines of code that I know use RxJS)