If the Willian links are real and there's genuine interest from our side, I can see there being more impetus for VdV moving on, but it's still too early to say.
My guess is that Willian would be considered more as a back up / alternative to Bale or Lennon.
If there is any truth in the reports about VDV leaving, however, it does make Sherwood's presence at the Malaga game last night all the more interesting. Because Isco would be more of a like for like swap (from what little I have seen of or know about him).