There are different levels of "errata" or "card interpretations".
With Nomad Camp, the description in the rulebook did say that it goes to your deck instead of your discard pile, so it was just a matter of the card not being technically accurate. That has always been the case with a number of cards, and has never been considered "errata" as such. Black Market even used to be missing the instruction to play Treasures, but it was stated in the official "rule note" that came with the card.
Envoy did get a kind of errata before being changed in print, but this errata was actually printed in the Adventures rulebook, when it first mattered. Salvager also got this kind of "errata" (or clarification) in the Alchemy rulebook, because it used to say "+$ equal to its cost" without specifying that it was the cost in coins, which didn't matter before Alchemy. Possession got a clear errata in the Empires rulebook (which was later superseded by the actual printed card).
Most of the cards that have been changed, however, don't fall into any of these two categories. The first time the change or "errata" appeared in print, is when the card was printed. Of course, the new version sometimes appeared in online clients before a reprint (and sometimes this version was superseded by a different printed version, making it never appear in print). Anyway, for these cards it's clear that players who play with physical cards can't be expected to play with different versions than they have (which I would expect the majority of them to not even know about*). Donald has admitted as much. So yes, printed old Cellar and old Oracle should work as printed - unless of course the players decide to play them as the new versions.
* Actually this discussion is moot for those players who don't even know about new versions of their cards, because they necessarily have not read about the cards online so there is no reason to consider what they "should" do. This discussion only concerns those players who own old printings and read about the new ones.