One of the biggest shocks of the nijisanji drama this month was Pomu quitting before Selen and not the other way around.
What we dont know is by going back to school is she actually going to college or by going to school she is enrolling to Vshojo after graduating from Nijisanji. There are vary old 4chan threads of Pomu pursuing her career in idol stuff .
Reason I think by enrolling in school she is talking about enrolling to Vshojo is.
1. Money. here are examples.
This is not counting one of them streaming on CB, along with others that have patreons and OF accounts. Also thanks to Aethel( I am sure that him and nyanners have gotten pissed off private DMs) he was the 1st twitch Vtuber to show his merch sales of making 55k in one week not counting the cuts taken from it, and considering he is a male vtuber I am sure the females would make more than twice then that. If Pomu was seriously going to college then she has a brain of a fish while Selen(spending 80 bucks on some jap burger and 500 bucks on a michelen star restaurant along other projects she paid out of her pocket and supporting her parents) is salivating at the thought of joining Vshojo or going indie on Twitch which would still make her alot of money.
2, Based on the treatment that Pomu and Selen received from Nijisanji, I am sure they will be happy to give Riku the final middle finger as they takes portions of the nijisanji fanbase over to their side and their creent new EN waves are suffering.
3. even if she is going to college I dont think any side job would pay more than streaming whenever you want as a Vtuber and current big vtuber companies dont even care if you stream or not. If you somehow don't like your new job, you still kept your huge audience then making them disappear for not streaming for a long time.
Sadly Nijisanji would only give a shit or feel threatened if their JP members somehow start getting poached,