It is hard to keep a good convention down. One year after some of Hollywood’s largest studios stayed away from Comic-Con International, they are back in force from July 23. The biggest of them all, Marvel Studios, will return to the 6,500-seat Hall H, as will HBO with its latest superhero show and dozens of other studios with star-studded casts. Comic-Con’s line-up since the Covid-19 pandemic has been cyclical, with the biggest names staying away one year and then a large push the next...