Unfortunately, the dominance of Google Maps makes 1) more likely to happen for them - more likely even than 3) is going to happen for OSM. Or at least, that's what my gut feeling says.
A small-town or rural convenience store in most of the world is not even particularly aware of how urban shops (but actually not all that many, comparatively speaker) are adding themselves to Google Maps. So, 1) is indeed unlikely to happen. But because OSM editing tools for newbies, like StreetComplete, encourage people to add opening hours for all nearby businesses regardless of size, that information does make it to OSM.
In my own neck of the woods, if you are cycling around the countryside, you can not only find a nearby convenience store to stop for a drink or snack, you can even know if it is presently open. Meanwhile, Google Maps has almost none of the small shops in this region, let alone their opening hours.
Sure, I think in rural areas, 3) happens somewhat more for OSM than 1) happens for Google Maps. In urban areas, though, I'd guess that 1) happens far more often for Maps than 3) for OSM.
I'm also not quite sure how often large chains are importing their opening hours into OSM? Because quite a few of them probably do so for Google Maps (or at least - Google Maps often has their opening hours).
> I'm also not quite sure how often large chains are importing their opening hours into OSM
Very rarely, to almost not at all. Most OSM imports are still either roads, address points or buildings. PoI imports are very rare (to be almost non-existant)
Unfortunately, the dominance of Google Maps makes 1) more likely to happen for them - more likely even than 3) is going to happen for OSM. Or at least, that's what my gut feeling says.