Of course, the Tundra is a full-size pickup, while the Tacoma is midsize. This means that Toyota's truck platform needs to have a degree of modularity, similar to the company's TNGA platform that underpins both large and small cars. Toyota sources report that the shared platform is nearing completion, and we can expect to see a truck built on it as soon as the 2021 model year. If that's true, it's almost certain we'd see the platform hit the Tundra first. That truck's roots trace all the way back to 2007, and the truck is really feeling its age against the modern domestic pickups. We've also seen spy shots of a Tundra mule running around, trying hard to conceal what's underneath.
Toyota has done significant work to the Tacoma recently. It was completely overhauled in 2015, and Toyota just released a light refresh for the 2020 model year at the Chicago Auto Show. This leads us to believe the Tacoma might carry on as-is, adopting the F1 platform some time after the Tundra does.
Toyota builds the Tundra and Tacoma at a plant in San Antonio, Texas. There is also some Tacoma production in Mexico. Moving both trucks to a shared platform could potentially make production easier for Toyota at its plant in Texas. Unfortunately, we don't have any details to go on for what the new underpinnings will consist of. An educated guess from recent spy shots suggested that it might be a coil spring or air spring setup in the rear — keep in mind, that's pure speculation at this point.
This also brings up the question of a Sequoia redesign. That SUV is largely based on the Tundra, so a refresh to that platform could mean the Sequoia isn't too far behind. For now, there's no concrete information on that one, but we can assume something is in the works.
If the timeline suggested in the report is true, we can expect to see this new F1 truck platform revealed in 2020. Electrification in some form is expected to be a part of the equation, but we'll need to wait to learn more details. It's certainly an interesting move to put different-size pickups on the same platform. We just hope it doesn't come with compromises to both trucks.
Update: Toyota returned our message for comment with an official statement: "Toyota New Global Architecture (TNGA) has been successfully implemented on many of our new cars and SUVs. While we're always exploring ways to improve upon our efficiency we have nothing to announce in regards to trucks at this time."