Can an art house movie significantly boost IU's international popularity?

Yes it would. The buzz it created just from the news that IU will join the movie. I heard she'll be a mother in the movie. Excited for it

EMPRESS IU WORLD DOMINATION!

Yes, her international fanbase will grow a lot, i'm so excited

Ooh this sounds interesting! Shoplifters was an excellent film.

This sounds great! I find her really charming as an actress, theres something very likable about her.

lets get it Queen

Depends on a lot of things. If it gets wide distribution, a lot of Hollywood buzz, and depending on the status of the pandemic in its release, gets nabbed by a streaming service and marketed properly then yeah. Also, perhaps drop the "art house" description as general mainstream audience is not that receptive with such films.

Whoa.... IU is really on another level

Raining PAKs and dropping casting news like it's nothing. WORLD DOMINATION!

The cast is really great. I think it depends on whether the film will make buzz or not. Lots of art house films just fade in the background and only lucky ones make buzz and get talked by both critics & general public. The film will of course be high quality looking from the director & casts.

As an actress yes

As a musician I doubt it. Acting careers does not help musical careers