I wanted to share my perspective on this Brady thing, because I hear a lot of fans who presumably are older (35-40+) who don't fully understand the impact this is having on younger people.
I was born in '95, making me 25 right now. My first memory of watching the Patriots was the 2001/2002 divisional game against Oakland, the "tuck rule" game - I was about to turn 7 at the time. My dad was happily rooting for both teams, as he is a Michigan alum and watched Brady and Woodson play in Ann Arbor. He always had a soft spot for Brady and thought highly of him at Michigan. Following the Patriots victory, he began to follow the team more closely given the Brady/Michigan connection, and gained a soft spot for Belichick and the way he ran the team. Note that we lived in (and still live in) central Virginia at the time; my dad couldn't root for the Ravens, because he grew up a Baltimore Colts fan, and he couldn't get any traction rooting for the Redskins and their awful management.
As I transitioned out of early childhood and into middle school, naturally I gained a greater interest in the Patriots, the team my dad watched as I grew up (albeit casually), and taking autonomy over my fandom, basically. It was the 2007 season that sparked my interest, as my 12 year old brain was infatuated with the Randy Moss acquisition. Beginning that season, I became a diehard Patriots fan. I watched in 2008, when Brady was out with injury. I cried after losses and rejoiced after wins. I was fully and completely invested, but as I described above, my path to becoming a fan was a bit unusual.
Fast-forward to today, and needless to say this is a challenging thing to navigate mentally. While I always identified as a Patriots fan, and loved Belichick and all the players who contributed to the team's success, naturally my identity as a Patriots fan is intrinsically tied to Brady, given my age, perspective, and the context in which I watched the team. I quite literally have ZERO memories (save for Cassell and Garappolo) of any other QB playing for this team. 20 years. From age 5 - 25, my entire childhood, adolescence, and early adulthood, all was Brady.
So when certain people (most of them younger) cannot reconcile/comprehend their allegiance and identity as a Patriots fan, this is why. There are certain fans who quite literally do not have memories of a time pre-Brady, and their identity as a Patriots fan is intrinsically tied to Brady being the Patriots' quarterback.
Will I continue to root for the Patriots? Absolutely, there's too much history and attachment not to. I have a great deal of respect and admiration for Belichick and the way he runs his team, and I'm excited to see how the offense evolves with a different type of quarterback. But will I also continue to root for Brady? Of course. Who do I root for if they play head-to-head? Quite frankly, I don't know, but I think I'll find myself trying to be a captivated observer, leaning towards the Patriots.
At any rate, I wanted to try to share my perspective in the hopes it helps others understand why this is inevitably causing such cognitive dissonance for certain people, given their age, perspective, and context.