I expect him to hold on and get happily franchise tagged after this year. By my calculations, it should set him at about $19 million for that year, which is a king's ransom. After that he'll negotiate down to a more reasonable salary.
It's not a bad gamble especially when a mobile quarterback starts looking at how hard keeping a job will be in the eighth and ninth years of his career.
If he signs before the end of this season, he'll either be leaving money on the table or he'll be getting such a huge contract it'll break the team.