Playing another 10 years would mean Brady would be playing until he's 48, which no quarterback has ever done. At age 38, Brady is having by far one of the best seasons of his career and has shown no signs of slowing down at all. He's a legitimate MVP candidate who is in the top 5 in passing yards, touchdown passes and has a QBR of 118.4, which is nearly perfect. He's also 70% of his passes, which is also very hard to do.
If Brady keeps doing what he's doing to keep himself in game shape, there's no reason he can't have another handful of successful years.