Don't think so - did a lot of research on this as had the rcd300 and iPod prep in the armrest that I wanted to keep.
Changed head unit to kenwood dnx520vbt a couple of weeks ago and rang round a lot and searched web. Your only option (I believe) is a vw mfd2 head unit if you want to keep the iPod prep - even if you went for an rns510 you would need to change to the mdi armrest connection (I stand to be corrected).
A lot of aftermarket head units have rear USB connection though so could just put lead in glove box or route it to arm rest.
The VW iPod connection isn't great anyway (5 playlists???!) - I sacked mine off