Because the Brand Koetsu has ceased, does not yet mean the members of the Family have stopped caring for the Brand.
There is the strong possibility a aftersales service is to be offered from a competent member of the Family.
They might also become a Patron of the Legacy and be quite valuable as a resource to prove a Fake has been produced, this in not strange in the World of Art for deceased painters who have died less than a 100 years past.
Koetsu has a extremely broad customer base, I am sure there are quite a few who would fully understand and welcome the Families extension of support for both Service Requirements and Authentication.
Certificates could be supplied by the Koetsu Family to explain the trueness to Original Spec' following Servicing / Overhaul, which in its own right as a Koetsu Supplied Document will prove provenance.
As this Brands Products are likely to substantially ascend in value over the next few years, such a practice will make it much much harder for the Fakers, as any purchase could be carried out pending Koetsu supplying Provenance or proving Provence Cert' is an authentic document.