Con: Brady will be quite expensive
If Brady does not re-sign with the Patriots, it will be because they did not offer him enough money. Brady has stated that he will not take a “home discount” from New England this time around, and he wants to be paid like one of the top quarterbacks in the NFL, something he has not necessarily required in the past.
The Raiders are in a position now where they have enough money to sign great free agents, and filling holes at wide receiver, linebacker, and cornerback have to be considered the priority this offseason. If the Raiders sign Brady, they will be missing out on some of these top players, leaving them with still the same amount of holes on both sides of the ball.
If the Raiders do not sign Brady, they could either draft a quarterback in 2020 or 2021, saving them even more money, or keep Derek Carr for at least another year. Brady is going to want great weapons if he came to the Raiders, which would mean the team would have a hard time spending money on defense, as, like the Patriots, the Raiders lack a true WR1.