By looking how their product line has evolved over the years, perhaps they have learned from past mistakes. Their latest lineup consists of 100% plug in discrete modules.
They have been building computers this way since the 70's. The reason why more manufacturers don't build their DAC's this way, is because they simply would rather have you buy an 100% new machine.
Let's look at Esoteric for example. I recall 1 member has recently upgraded from the K-01 to the K-01X. This required buying a whole new DAC. I can imagine he took quite a big hit in resale value selling the old K-01. Great example here. A few months old and selling for 1/3rd original price:
http://www.hifiplatform.eu/uk/2e-hands-hifi/43-cd-speler/1061-esoteric-k-01
And now 1 year after the K-01X was released, AKM now has a much better AK4490 DAC chip available. Their flagship product doesn't even have the flagship DAC chip. But their lower end ones do. This is because they are newer and released after the AK4490 was. So how long now till we see the successor to the K-01X? 2 years?
The Resonessence Mirus was released in 2012. When ESS releases their new state of the art successor to the 9018, Mirus/Invicta owners simply will have to swap 2 credit card sized boards, download a firmware and copy to an SD card, pop it in the SD card slot, and upgrade. Now you have the latest and greatest Circa 2016 Resonessence Mirus. That uses the chip competitors will have to replace their whole DAC lineup to offer new products with.
Now this is a smart way to build a DAC.