Excellent post.
No doubt Brady as he is right now would beat Garoppolo out in a straight up competition for the same job. If we could count on Brady being what he is right now for each of the next 5 years the decision would be a no-brainer.
It would also be a no-brainer if the Superbowl was the only practical objective. Other objectives we have taken for granted for a very long time include making the playoffs, winning playoff games, being an entertaining product to watch, and making the owner money. These are objectives that other franchises can't take for granted in quite the same way, and objectives that having a reliably good quarterback, even if he isn't a great one, can help a franchise achieve.
These are the objectives that require "After Brady, who?" to have a legitimate, well-considered answer. Just because we take them for granted now does not mean we'll always be able to. I'm sure the San Francisco 49ers thought it would go on forever too, especially after Steve Young took up the torch so well.
These are the assets that Bledsoe gave us and why his presence was actually a big advantage to the franchise even though he never managed to be more than a good quarterback himself. (I've said in the past that after the Brady era we will probably look at the Bledsoe era more charitably; this is what I'm talking about). This is why Bledsoe was a necessary stepping stone to the Brady era. It was the team we tried to build around our good-not-great quarterback that our unanticipated legend took to the Superbowl. Without the Bledsoe era, Brady may not have had the talent around him to even show us what he had.
It's also why, if we step off the all time great era into another respectably solid quarterback's era in the person of Garoppolo, we'll have done fairly well for ourselves. At the very least, Garoppolo would be good enough to keep the Krafts in business, keep Foxboro as a destination worth going to, and give the team a chance to keep rebuilding itself and competing for the top. And you never know. We may all be underestimating the hell out of Mr. Garoppolo. Not like it hasn't happened before.
Right now Brady is as good or better a bet to meet all of these objectives compared to Garoppolo as well as his vastly superior odds of winning a Superbowl. But if winning the Superbowl ever comes off the table sometime in this lifespan, due for example to severe decline on Brady's part, or due to a failure in team architecture or aging, injury or disappearance of key assets that prevent Brady from being able to put the team over the top (if the Patriots make some big mistakes in the draft and wind up spending a few years in Breesville for example), Garoppolo can be expected to have a growing, and eventually superior, chance of meeting these other objectives. He'll be developing and getting stronger, especially if he is given (and proves up to the task of) a starting role so that he can really start gaining big league experience, while at the same time the best Brady might have done is a heroic effort of self-maintenjance.
Again, it's a balancing act. The ascending line and the line we expect to be descending soon will eventually converge. The decision of what to do is based almost entirely on WHEN you expect those lines to meet.
