His form will almost certainly drop next season, so probably good for both parties to cash in soon.
I think Higdon is the only on-form striker to have a semi-decent strike rate (14) the season after he left us. The others like Sutton, Moult and Watt have all struggled for various reasons.
(I'd be delighted if he stayed, of course, but his recent interviews sound like they are laying the groundwork for moving on).