That's not what mozilla is changing with this policy change. You've had to either sign or temporarily load an unsigned packed/unpacked extension for a while now.
Pretty much. There's a preference you can change to allow unsigned extensions, but it only works in dev/nightly firefox and "unbranded editions" of release/beta firefox.
> Note, however, that your add-on may still be subject to further review, if it is you’ll receive notification of the outcome of the review later.
So other than hosting, I fail to see how this is different from distributing through the official channel — you still have to pass their review.
Note that I’ve never written a Firefox add-on (I’ve written plenty of Chrome extensions though), so please correct me if I’m wrong.