I really like this sort of 'advertising'.
First of all because chalkboards have a very authentic and spontaneous appearance: Whatever is written on it, it seems like it is written this morning. By the girl that's now working at the counter. It doesn't look like overproduced marketing. This is a message 'only here, and only now'... witnessing some of the EXKI empathy for local consumer behavior, partnering with UGC cinema right accross the street.
When we look back at the early marketing of Starbucks, the chalkboard was (and still is!) one of its main communication channels. All new products and taste varieties were introduced on the chalkboard. First of all, it always looked "new", and was a trustworthy and real conversation starter.
Imagine Starbucks decided to launch all its new coffees into mass media (just like Mc Donalds does with every new burger), consumers would think that everyone has seen it on TV.
Asking: "do you know this new frappucino at Starbucks?" would feel a bit silly.
It wouldn't be flattering anymore to talk about the new Komodo Dragon blend,
or Caffè Verona you can discover just around the corner.
Therefore, reconsider the chalkboard. At least, it feels like someone really wants to tell you something.