Thank you. Anybody who has any influence in the discussion, please help to make this clear. It is important for the researchers, I think. In this particular case arXiv is by no means "small" (has 1.4 million articles) but is non-commercial, What about Figshare which may classify as commercial? Other platforms?

Two more examples examples for arXiv and one for Figshare. (1) Article in journal has a flaw. For some reason the journal is slow or unhelpful concerning a correct version, so the author posts on arXiv a revised and perhaps much bigger version. Filters (will these be on arXiv?) detect a copyright infringement. (2) I translate an Euler article and post it on arXiv (with all attributions). Or an English translation of an obscure German or Russian article by a great mathematician. (3) I post on Figshare (and GitHub?) the meat of a published article (like data, procedures, results of experiments, programs) in order to make the research Open Science. I explain the context but maybe I don't pass the automated filter which detects a copyright infringement. For all examples, same questions as before.

Example: article in arXiv gets later published in a journal. Will the arXiv article version be still available for anybody? Only for non-EU people? Will be removed from arXiv? None of these?

Right, will arXiv implement such filters? Same question for other green or gold OA platforms. We all know about Elsevier, but if I put my paranoid hat then for gold OA this is even more perverse, will they try to kill green OA (not that I believe in this failed classification which separates between green "repositories" for archiving and gold publication platforms). Anyway arXiv is a monument which has to be protected from this madness.