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

I'm wondering the same thing---looking to upgrade from my Marantz ND8006 streamer/CDP. It's been good but would like to move up to an AURALiC or Lumin.

One opinion here - No. There is always something to improve and advance the state of the art. I purchased a five year old DAC that was rated A+ at the time. Now it's not even in the competition. I think it's great, but will probably upgrade in another 2-3 years. 

“At the end of the day, DAC is a digital product.”

With that outlook, don’t bother to waste your money on an external DAC. You are only adding an expense of power cord, digital cord for not much gain. If you can’t help wondering, buy a DAC with a return policy to scratch your itch :-) 

If you like the sound of that amp/dac then don't worry about better just enjoy. Also that to me is one of the downsides of the amp/dac combo you're basically stuck with that Dac or you paid for it but you're not using it.

No

Maybe, maybe not.

Forever?  Who you crappin'?

Streamers have only proliferated for 

11 years since the Aurender S10 came out.

And I would never buy one enclosed with a DAC.

Knock yourself out.