Either it is a free market, or it is essentially Marxism.
Call it whatever you want, but the alternative to the free market is an authoritarian command economy with little freedom. The hope that new and higher levels of technology will change that is a pipe dream.
There is nothing that can artificially replace the trillions of intricate, infinitely complex social-economic decisions at every level of the economy that makes the free market superior. To act otherwise is to have to learn, again, another painful historical lesson in economics.
And the Marxists do try to re-name themselves every so many years in the hope that something will eventually stick. Today it is “Progressive”.
If you said socialism you might have a good point. Marxism is a theory for one variant of socialism, but it's not the only one.
Conceivably, all Marx's predictions could be proven untrue and rejected, but there would still be some kind of socialism or some sort of anti-capitalist impulse.
It reminds me of the routine about Halloween costumes on Community:
Troy: I'm a dracula.
Abed: You mean a vampire?
Troy: I don't need to know which dracula I am to be a dracula.
Marxists are socialists, but I don't think all socialists are necessarily Marxists.