Artist's commentary
Kessoku Band in 10 years (Bocchi the Rock!) Party
A lot of things will change in 10 years. No matter how you don't want everything comes to an end†, everybody has to pursue their dreams regardless. Maybe Bocchi got rid of‡ her introversion and became a successful YouTuber. Starry was no longer in business and Kita, who is good at socializing, drifted away from music, while Ryou became a top musician with her inheritance.
† In Japanese, "Kessoku" means "to join," "to bind together," "union." While in Chinese, the same kanjis "Jieshu" means "the end," "finish," "terminate," "finale," and the such. This is one of the rarer cases that the same kanjis, although share the same writing, have totally unrelated meanings in Japanese and Chinese. The artist's comment used this linguistic discrepancy and primarily took its Chinese meaning.
Chinese translators took different approaches to the word "Kessoku." Some used notes (like this) to explain the discrepancy while preserving the original kanjis, while others properly translated it but left viewers confused about the "Kessoku/Jeshu" wordings on screen.
‡ The artist made a typo.
Yajuu-senpai was also featured in the background as he was closely related to Shimokitasawa. Propaganda posters also feature symbols of the Japanese Communist Party, although no tags could be found relevant to these.