I'm not really good with Japanese, but I have read that both Kubo and Masashi Kudō (adaptation from manga to anime in Bleach) are working on an original filler due to broadcast this July in a recent interview. This was reported in several Japanese blogs just this week. Seems that this filler will focus on the theme "incarnation of zanpakutō (斬魄刀の具現化)". It's not very clear what the actual story will be about, but it guess it will revolve around the spirit forms of the shinigami's weapons.
Blog links: http://kyuuchannel.blog21.fc2.com/blog-entry-732.html, http://blog.livedoor.jp/poppy_moon/a.../51133001.html
OMG, a filler arc Im wanting to see? Le gasp!
EDIT: The part about Shirayuki was just speculation by the blogger, not official. But there's still hope.