The Kobo Aura H2O Edition 2 came out in May 2017 and it is completely sold out on the main Kobo website. Many bookstores that stock Kobo products are also reporting that they no longer have this model in stock on their website and their retail locations are hit or miss.
Normally when Kobo is sold out of a product and has placed a new order with their manufacturer they will have an estimated date when it will be available again. There is no date on their product page and people who have placed an order before the product was sold out has not received a tracking number.
Has Kobo decided to discontinue the second generation Aura H2o? I have not heard reports about this device being so popular that they cannot meet demand. What is interesting is that the first generation H2o is still available on their website.