I'm sure the most shocked are the new-ish fans who got into Momusu during the 9-8nin lineup that finished last December. Ok, I'm a new fan too, but at first I cared more about the OGs, and only started to really care about the current lineup when Rival Survival had started and I knew to not become too attached to Eri, Jun or Lin. So let's say I'm as excited as a little kid about these auditions.
Now for some actual information, according to translations, the title for the auditions is Genki Jirushi, the date of applications submissions starts today and finished on June 13th. The age, if you're interested in applying, is from 10 to 17 years old. I've also read that the chosen will be two girls, and that they'll be introduced at Ai-chan's graduation concert, but it seems those are only rumours.
It's also a rumor that Gaki may be graduating soon. But, because she'll be in fact the leader, I actually hope for her to last around what Yossy lasted when she became leader. Even so, a graduation for her, Sayumi, Reina and even Aika should be really expected and not take anyone by surprise.
Even if I actually want Reina to be gone... Yeah.
As for my expectations, I hope for this generation to bring even more personality into the group than Zukki brought, and a vocal ace wouldn't be any bad. I wonder if the left eggs will be allowed to audition, as with the last audition? Which reminds me, Tsunku, we NEED a new Egg audition!
And other than to say I'm glad that it's now that I entered the fandom that MM is going back to the previous custom of regular audition/graduation, I've got nothing to add.
Official Site for the Audition (in Japanese): http://www.musume-audition.com/
Sources for the news:
Hello! Project official site: http://www.helloproject.com/news/1105081630_musume.html
Hello! Online thread: http://www.hello-online.org/index.php?/topic/21791-morning-musume-10th-gen-audition/
TokyoHive and Aramatheydidnt @ LJ should be useful too.