Lately we have seen a lot of models just not available with Brettonia, and yesterday on the UK site, even the armybook is not available. I did check other countries, and it appears that the book is still available on the US site, and AU sites.
Its most likely that they are running low on stock, even though they are being listed as "No Longer Available" on the site. This has been an issue a lot lately, of products listed poorly giving us the impressions that items that are out of stock, are no longer available.
The rumors of course on the Brettonia are next to nothing right now. Past rumors have had them being rolled into Empire for a Fall or Winter release. Until we get closer to that, I fear that the fate of Brettonia will not be known.