There are other ways to do subshells than using the same syntax, just that the Fish developers never did it, maybe because it's not requested enough. I think it's still the most annoying thing about Fish, and the most convincing reason to switch away again. I frequently drop into bash to do
(cd subdirectory && command --that might.fail) && run --command-in-original-dir --only-if-subshell-succeeded
... and expect to still be in the original dir when it's done. Any solution in Fish using "&& cd -" at the end of a block AFTER a maybe-failing command is just wrong, and there seriously isn't any way except saving and restoring $PWD every time you want subshell functionality, or using "; cd -" and manually saving the $status, which is equally as frustrating.