There were a lot of people who were adamant the Pats don't trade Jimmy G because Brady will retire in a couple of years, and then the Pats dynasty will go on for 15 more years with Jimmy. That was right after the Falcons SB. People were fully convinced that inserting Jimmy instead of Tom will get you the same results, more or less. People actually watched SB 51 and thought, yeah, the QB is replaceable.
The counter-argument was, Brady is once in a lifetime player, you trade Jimmy for a high pick/s, kick the tires on Brady by giving him the best possible weapons and content for the SB every year until he retires, once he does you draft a QB and become a regular team like everyone else.
Well, time has answered very well who was replaceable and who wasn't.