The large crownwheel support bearing is a C3 bearing but obviously there is some tolerance for that clearance as this rear wheel play, or its absence, is something that has been noted fairly regularly over the years. Some bikes exhibit it, some don't. There is really no other explanation.
The important thing is if the bearing does begin to fail, and this usually takes one of two forms of failure, the seal will begin to leak dramatically before the bearing has the opportunity to fail catastrophically. (Having said that one will probably prove me wrong next week!
The failures I have seen over the years have all been the result of either the balls and races brinneling
up or the cage disintegrating, both are rare after the very early bikes where an inferior bearing with only 17 balls was used, later bikes use a 19 ball bearing with a stronger cage design.
My advice would be to keep checking it regularly to see if it worsens but not to worry unduly. As I said if something bad is happening you'll loose the seal before you loose the wheel!