^You can't really compare both moment. When Yukari left, the band was relatively "young" while now they are +10 years and built their image and identity with MisaChia songs and boys's songs. As the members set their solo career going, I think that most of the fans who like the band because of one member will split and follow the singer they prefer while in 2007 they had to stay focused on the band because it was the only way to listen to him/her.
I like AAA but I'm realistic. It's already an "old" band and when members walk on their own way it's rare that the group continue to exist. I wouldn't be surprise if an indeterminate hiatus was announced in 2018.
edit: Btw I wonder if we should keep all the solo careers in this thread or open new threads for the members who releases CDs often such as Nissy or SKY-HI? What do you think ? Is it worth it?