The only way the C's get Howard is Orlando is stubborn/foolish and doesn't trade him to a team where he's agreed to sign an extension. (Lakers, Clippers, Mavericks, Nets) Every sign has been that they are going to trade him and are just waiting till the deadline to get the best possible deal and/or convince him to stay.
If they keep him then the C's would be unlikely to attract him, but we've have a shot.