The initial plan was 2 days. Then Spez did his AMA where it was clear they were not interested in compromising, not planning to change anything, even seeing the enormous protest forming.
So while some subreddits are still planning on 2 days, a growing number of them are going dark indefinitely until reddit rolls back this plan.
Also, quite some people seem to be removing their accounts along with all their post history. Maybe not in numbers that are significant to make it a ghost town, but in some subreddits you already see gaps appearing in prior discussions.
For some niches, Reddit's comment history is basically like a knowledge base and it's slowly being torn apart. If the group of signal-noise contributors that nukes their whole history grows, it devalues Reddit in another way as well.
I nuked 12 years of content. Yes i know its archived and like still available. But at least on the public site i withdrew my consent (my thought process/reason) for them to have my content that i can now only provide with thier completely shitty apps
Many are now committing to either going dark indefinitely, or to reassess after the 14th, maybe with a poll to their members on how to proceed. This will definitely be going on for more than 2 days.
I don't know how widespread the sentiment is, but some mods have decided after the disastrous AMA that they're going dark indefinitely, until Reddit walks back the changes.
It would not matter if that were the only thing occurring, but as a discrete event in a significant cluster of events, this leads to more awareness and more reassessments by communities looking at what value and future reddit actually provides.
Why only 2 days? This could happen again or it could keep going. Thus shows reddit what they are without all the freely contributed content and mod work.