I actually think Black Widow would do better than Tenet theatrically domestically simply because Marvel is obviously a way bigger brand name than Nolan at this point, however I don’t see Marvel doing much better than Tenet without key markets like Los Angeles and New York available.
BW would certainly would do better in China than Tenet given how big the Marvel brand is over there, but at the end of the day studios get a bigger percentage of the profits domestically than they do internationally. If BW did big business in China, BW would only get like 25% of box office there.