Is there such a thing as a FOREVER DAC/streamer?

Check out MSB Technologies. 

Let us know what you decide to do and good luck in this journey!

In my opinion, getting a quality setup now on the digital side is a worthwhile investment even if it might be surpassed in five years or whatever quoted timeline. Because one thing that is irrelevant is of time is having a setup you can enjoy. A component with good isolation, clean power supply, usability, etc will still be providing that same quality five years from now.

If a setup today makes you content for years to come, that’s what counts in my view in terms of making an investment.

No such thing really. 
however, some have firmware updates. 
Take the Lumin (I have a D2)… since I purchased, there have been several updates. 
it’s part of their DNA to continue the updates. For my non-vinyl purposes, this is possible my last streamer purchase. 
 

the PS Audio airLens looks quite interesting, however. 

+1@jeffreyw

Check out Aries Cerat

My DAC is my most expensive component, a PS Audio Directstream w/ streamer card. And I’m glad because streaming is more and more of my listening. It’s software-based, and they’ve issued a number of updates that are easy to make with just an SD card. But still … now they’re introducing a new version and will stop upgrades to the Directstream. So I suppose there’s no such thing as forever in digital. But I do think this source is so important that I’d still spend what it takes to get a great one.