Let's take your opening post bit by bit.
Brady has 5 or 6 years left to play
Nobody knows if that's true. He could play 1 more and walk away with a Super Bowl, he could play until he's 45.
and by then Mallett will be in his late 20's where you are expected to have 3 or 4 years of starting experience to be considered a franchise QB.
Ok you're right that Mallett will be in his late 20s. Beyond that you aren't saying anything of value. Every situation is different and right now there is little info to suggest that Mallett wouldn't be happy to stick around for a few years on the bench. That of course ignores the possibility that he is called into duty much sooner.
I see Mallett being a franchise QB though, except not in NE
The former is speculative opinion based on half a preseason game against a crappy team. He's not even as good as Hoyer right now.
, and you have to be wishing Brady to suck or get injured to think Mallett will ever be the face of the Patriots.
No you don't, you have to be realistic and know that the chances of Brady playing another 5-6 years at an elite level are likely pretty slim.
Mallett is not wating 6 years on the bench to finally start lmao
Probably not, but the chances of him needing to do that are hardly 100% which is what you seem to be implying.
So to your thread title of "Mallett will never succeed Brady" where it is an absolute, if you changed it to "Mallett likely won't succeed Brady" you may have made a decent argument. Oh and taking somebody calling a HoF quarterback coming off an MVP season "washed up" as a serious comment really didn't help your cause.
There are no "never"s in football. Troy Brown will never make it in the NFL as a WR. Tedy Bruschi will never make it. Tom Brady and Matt Cassell will never be more than a #3 QB. And so on.