Again, personal interpretation. A "crippling blow" is not one I consider to be fully recoverable.Since the blow was to transportation infrastructure, they can of course be either repaired, reconstructed or replaced entirely and the system rebuilt. Janeway saying the word "Crippling" obviously does not imply in any way that a new transwarp hub couldnt be built. They built the one that was there, why would they not be able to constuct another one?
I dont mind which species they have on as long as it is a good, well written story.
Again, I don't care for the Borg. They suck. They are overused boogiemen that are no longer scary. They were defeated again and again by an unsupported Starfleet ship. There is no reason to revisit them because they offer nothing new.