What I really want is another decade of BB coaching after Tom retires.
People forget that Brady wasn't always a first-ballot HOFer. He was very much that "game manager" type in the early days. In 2001, Brady completed 64% of his passes for 18 TDs, 12 INTs, and under 190 yards per game but we still won the Super Bowl. During the play-offs, he would throw 1 TD, 1 INT in 3 games. In 2 of those games, he didn't break 150 yards passing, although he was injured in the Pittsburgh game (thank you Drew, always, for that).
He would improve steadily over the next few years, developing into a top-10 QB but certainly not a GOAT contender until near the end of 2004 I'd say. Some might say 2005, some might say 2007. The point is that he developed into it, and a huge part of that was having the same system, the same coaches, the same consistency around him.
Alex Smith was a total bust after his first few seasons, but he also went through 7 offensive coordinators and 3 head coaches in 7 seasons.
Few QBs start on day one and we know they're going to the HOF. Manning had an up-and-down first season but by the end, you knew. Luck is another guy. Then again, RGIII looked like one too and that went off the rails quickly. The rest end up having to develop.
Montana didn't become a full-time starter until his 3rd season. In his second season, he started 7 games and showed some flashes, including a 64% completion and 15 TDs vs. 9 INTs, which was promising. Troy Aikmen went 0-11 as a starter his rookie season, and didn't throw more TDs than INTs until his 3rd season (11 TDs, 10 INTs). Terry Bradshaw didn't throw more TDs than INTs until his 6th season, which just wouldn't happen in today's NFL because you'd be long gone by then. Drew Brees didn't emerge until his 4th season, and only after the Chargers had given up on him and drafted/traded for their next future QB.
The point is that whoever the guy is, he will likely need a stable base and team to help him develop and mature. We've seen BB develop someone like Cassell, and who knows? Maybe if he stayed here, he would have turned into more. If Bledsoe didn't get hit so hard, we never hear of Brady. If Rivers never holds out, he gets handed the starting job over Brees, who never emerges. If Pittsburgh shows less patience in Bradshaw, he gets cut well before his 6th season.
Whoever the next guy is, we will need to surround him with talent and stability. We need to encourage development and continue to push them towards greatness. Part of that will be drafting the right guy (and maybe we already have). But part of that is on the FO as well, and I hope BB will remain part of it to transition us from one HOFer to the potential next.