I think Magennis will probably make it through, moving into the front row as he gets more experienced. I haven't seen anything from Ashurst as of yet to suggest that he will be kept long term by Saints.
In regards to Eastmond to Wakefield, if it means us brining in a replacement early then I don't see why not. However, if there's nobody to replace him it would be stupid to send one of our only half backs who is going to be fit any time soon.