Jimmy Garoppolo was supposed to be the Patriots’ future. He’s gone, so now what?

Tom Brady is 40. It’s a unique, Tom Brady version of 40 fueled by avocado ice cream and definitely not by coffee or strawberries. Whatever he’s doing is working and he’s playing at an unprecedented level for someone his age.

He leads the NFL in passing yards after eight weeks and is still very much an MVP candidate, so it doesn’t look like Father Time is sneaking up on him. But he’s still 40.

Eventually, his Hall of Fame career is going to come to an end. At this moment, there’s nobody waiting in the wings to take over. Trading Jimmy Garoppolo to the San Francisco 49ers on Monday — two months after sending Jacoby Brissett to the Indianapolis Colts — left Brady as the only quarterback on the roster.

Finding a new backup quarterback won’t be too hard and won’t take long. Likely by Tuesday, the Patriots will scoop up a veteran — Brian Hoyer or T.J. Yates, perhaps — to fill that void. But neither will be the future of the position for the Patriots and franchise quarterbacks don’t grow on trees.

Presumably, if the Patriots were willing to trade Garoppolo, it’s because the team didn’t think he was that player. A 2018 second-round pick as compensation certainly indicates that the Patriots didn’t think that highly of their 2014 second-round pick.

But it may just be New England recognizing the precarious reality that keeping Garoppolo was going to be a logistical nightmare.

He made two starts in 2016 when Brady was serving a four-game suspension and played really well. He threw four touchdowns with no interceptions before an injured shoulder sidelined him. Other than that, Garoppolo’s regular season playing time has been limited to clean-up duty.

Maybe the Patriots were unconvinced by what they saw on the practice field and in meetings. Maybe his shoulder injury raised injury red flags.

But the likeliest scenario is that his play in 2016 shot his value to a level that New England couldn’t keep.

Garoppolo is due to become a free agent in the 2018 offseason and wasn’t shy about talking about his itch to start.

”I wouldn’t say I’m frustrated,” Garoppolo told The MMQB in July. “Eager to play is probably a better way to put it. I’m just not used to being a backup. I want to be a starter, and compete to be a starter.”

As long as Brady is still playing like Brady, that’s not an option.

So how did the Patriots plan on keeping him around? Quarterback-needy teams like — oh, I don’t know — the 49ers, would’ve been ready to offer a huge amount to a prospective franchise quarterback hitting the open market. New England couldn’t possibly justify dishing out an even more attractive contract that convinces Garoppolo to stay and sit longer.

There was always the option of the franchise or transition tag, but that would’ve guaranteed Garoppolo more than $20 million for the 2018 season. And then what? If Brady plays until he’s 45 — like he hopes to — how long did the Patriots plan to juggle the situation?

By trading Garoppolo, the Patriots get a second-round pick and start the hunt over again.