There's no way it misses $400m, it's predicted to be at $300m by this Sunday: https://mobile.twitter.com/GiteshPan...4pjpRZQeQ&s=09
I'm not sure what numbers you're looking at but most box office pundits agree $400m is all but locked. $410-420m is the consensus for the bare minimum it'll finish with. Comparing it to TDK and TDKR makes no sense when they were sequels and this isn't. 9 times out of 10 sequels always outperform the 1st entry in a rebooted franchise. If you want to compare it to the Nolan trilogy compare it to Batman Begins. The Batman will make more in North America than Begins ($373m) made worldwide.
The Batman also debuted in China on Friday with $3.6m which is better than what was forecasted, 2/3 of theaters are shut down there so it's pretty good under the circumstances. Even better is the reception, it has a 9.0 on Maoyan, China's version of Rotten Tomatoes. That's the same audience score Infinity War got on Maoyan and better than No Way Home's score which was a 7.9, word of mouth should be good. All the talk of Batman not being popular in China and this not being the kind of movie Chinese audiences would like might've been a little premature.