I believe the us-open tag can be used in a similar fashion to the world-cup tag.
@jamauss says the we've had questions specific to the US Open before. I found one and added it to the us-open tag.
Also, I have updated the tag-excerpt for the us-open to state (as the previous one was more-suited for a tag wiki, and has since been moved there):
Questions about the US Open. This tag shall also be combined with a tag for the specific sport in question.
For any further information, a user can view the tag wiki.
This doesn't delete the tag as there are questions specific to the US Open nor does it specify itself as any one given US Open (unlike world-cup where the tag specifies itself as the FIFA World Cup). This also doesn't obfuscate things. However, I am open to further discussion and consideration.
In regards to the super-bowl and world-series tags, I believe those tags can also work if specified in its tag wiki. That is, super-bowl as NFL's championship game or world-series as MLB's championship series. Or, if we want world-series to cover all such events (such as MLB's World Series and The World Series of Poker -- just an example), then we can require the tag for the specific sport in question.
Looking at the snapshot below, the us-open tag appears to be is useful. The questions are specific to the US Open and tagged with the specific sport in question. Does this convention work? Related discussion