While it is understood Hartley has a two-year deal with Toro Rosso, the team admitted earlier in the season it looked into replacing the Kiwi with McLaren junior driver Lando Norris. At the time Hartley had made a couple of uncharacteristic driving errors while the team's inability to give him a competitive car meant good results were not forthcoming.
But Hartley has shown significant signs of improvement in the past few races, often making the best of a bad situation and working hard to get his car further up the grid than it maybe deserves to be.
He is known to be very good at providing quality feedback on the car and engine, which is a big help for a team that is in the first year of a partnership with engine-supplier Honda.
Red Bull will also use Honda engines from 2019, which could mean his knowledge of the equipment could be invaluable as the team makes the transition.
Hartley is also the consummate professional. He has remained calm and measured throughout his time in Formula 1 thus far, worked hard and not been outlandish with his media appearances. He appears to be very popular and is well respected in the paddock.
With Sainz Jr and Toro Rosso engineer James Key making the move to McLaren for 2019 it would not surprise if part of those agreements were McLaren releasing Norris to head in the opposite direction, although no confirmation of that has been given.
But even should that transpire, Hartley could retain his spot as an experienced driver that will focus on car development while Norris finds his feet.
A couple of months ago it seemed Hartley would struggle to see out the season in Formula 1 – now it appears he will continue his dream in 2019 as well.