As a tangible, seats for a performance would still be scarce and other such things, as would things with the quality of 'originality'. A replicator can make a perfect replica of the Mona Lisa but it is still not THE Mona Lisa.
That's a great topic for a philosophical debate. Let me take the counter position. First of all, this quality of "originality" you mention is impossible to quantify or measure. If I send the Mona Lisa through my nano-duplicator, and it recreates a second Mona Lisa identical to the original down to the brushstroke, down to every last pigment, down to every last molecule and atom, then you would have no way to distinguish between the two of them. If I put my nano-assembled Lisa on the wall at the Louvre, and no one was able to tell that it was a duplication, then it seems to me that they would have the same experience of having seen the Mona Lisa, had whatever personal experience with the artwork that they would have had with the original.
If this quality of originality cannot be demonstrated, if its absence makes no difference to people who encounter the work without knowing its providence, then what difference does it ultimately make whether or not the work was created by da Vinci in the Renaissance or me with my nano-assembler? What is this quality of originality, and why should I consider it?
Second of all, even when we know works of art are replications, it doesn't universally hold in other arts that a duplication is less worthwhile than the original. I have on my bookshelf in front of me As I Lay Dying
. It is certainly not a first edition of the book, published in 1930. Nor is it Faulkner's original manuscript. My edition was published by Vintage Books in 1996. Yet the contents of the book are the same; it is the same story that contributed to the body of work that won Faulkner the Nobel in 1949. Even for a work I know at a glance to be a recreation 66 years after first publication, the work affects me no differently than if I had read a first edition, or even the original manuscript. What would I gain by reading a first edition or the manuscript? Consequently, what do I lose in my Vintage edition?
But I digress. Communism, yeah? Still against it.