Maurice Jones-Drew can hold out all he wants. From what I've been told, there is no consideration at all on giving him a new deal.
This has the potential to get ugly if Jones-Drew sticks to his guns. He has two years remaining on his contract, but, he could report late into camp, and assume his normal role. Whether he does or doesn't, his backup Rashad Jennings is a definitely a guy to target in your draft. That's especially true if you're keeping Jones-Drew, or you draft him before he reports.