If it detaches, there's no way for the orbiter to bring it back. This was a one-way trip. But it should already have interesting data.
ETA: Apparently, Philae landed and started sending back information on the surface it encountered, then "bounced" and relanded.
ETA ETA: then bounced and relanded AGAIN.
ETA ETA ETA: then it landed on its side against a "rock" face. It isn't anchored, but its down, and otherwise functioning as expected.