When there are no more people alive that have love for the machine I guess
Once Upon a Time in the West and Kelly's Heroes are two of my more or even most favourite movies because my dad loved them to bits and thus shared them with me with much enthusiasm from a very young age. If he hadn't, I might have seen them but they likely would not have imprinted on me in the same way.
You see younger people who were born after "the demise" that still show an interest in and even develop for the Amiga. I can only guess that this is the same kind of transference of enthusiasm going on, they have a relative that opened their mind to it. Of course everyone is different, there will be differing motivations to want to program for or play on old hardware. But having played on an Amiga on your dad's knee or even seeing their creations on it is an unbeatable motivation.
But that is where I personally draw the line. That transference is not going to happen to the next generation or at least not with the same amount of success as it has happened from our generations to the next. At some point the Amiga platform is going to be purely something for the museum. But not yet. Not for a long while I'll bet.