The energy drinks firm have a trio of extremely promising youngsters to choose from when selecting Max Verstappen's 2015 team-mate. But, given the Dutchman's unique lack of experience, they may elect to retain the services of a relative veteran who already knows Toro Rosso inside-out.
Here are the contenders for the seat.
Carlos Sainz Jr.
The initial favourite, 20-year-old Carlos Sainz Jr. fits the Toro Rosso bill perfectly. He is young, marketable, and fast - a Red Bull dream - and was long viewed as a shoo-in to join the junior team until Verstappen was handed the promotion at his expense.
That was a major shock - and not just because of Max's age. After a few patchy years, Sainz has fully delivered on-track this season, becoming the youngest man to win the competitive Formula Renault 3.5 championship while also setting new series records for wins and fastest laps.
But, with Verstappen in situ, the Spaniard may be undone by the fact that he is an F1 rookie. There appears to be a feeling inside Red Bull that pairing Max with a fellow novice would be bad for the team - which effectively rules Sainz out. One could also question just how much faith they have in a driver who has just recently been passed over in favour of a 17-year-old in his first year out of karts.
However nothing has yet been set in stone - publicly, at least - and if Red Bull want to promote one of their rookies to the Toro Rosso seat Sainz is the standout choice. And even if he is overlooked, the 20-year-old continues to be linked to a Caterham drive - assuming the team exists next term.
Red Bull's apparent desire to give Verstappen an experienced benchmark should be music to the ears of Jean-Eric Vergne. It was always clear that JEV was heading for the exit this year, but the departure of Kvyat to the senior Red Bull team may have granted him a reprieve.
That would be a sensible decision - and one we argued in favour of a few weeks back. This is not a sympathy vote designed to save Vergne's F1 career, but rather a way of ensuring that Verstappen has the best possible environment in which to learn the F1 ropes. Using the fast, experienced Frenchman as a benchmark makes absolute sense.
It is worth noting that Vergne has been quite vocal in his frustration at Red Bull, both for ending his Toro Rosso tenure and promoting Kyat to the senior team at his expense. It is not impossible that those words could come back to haunt him when they make their decision.
However he remains the most suitable candidate, albeit through endurance rather than outright speed. If he is retained he would be expected to give up his seat in FP1 several times, but considering how close he came to dropping out of F1 altogether you have to feel he'd grab his second chance with both hands.
If Red Bull elect to promote one of their rookies to Toro Rosso but decide that Sainz is not the right man, the favourite must be Britain's Alex Lynn. The 21-year-old won last year's Macau F3 Grand Prix and is now on the brink of securing the GP3 title in his rookie season - just as Kvyat did 12 months ago.
But Lynn, like Sainz, has been leapfrogged by Verstappen, and will be hampered by the presence of another rookie at Toro Rosso. Despite his best efforts, a promotion is unlikely to be on the cards for 2015.
However all is not lost for the Brit. Winning GP3 would effectively guarantee he stays on the Red Bull roster for next year, which should result in a switch to either Formula Renault 3.5 or GP2 with a front-running squad. If he's successful in this endeavour he could get some F1 seat time and may yet graduate to the top-tier in the coming years.
18-year-old Frenchman Gasly is a rank outsider for the Toro Rosso seat. That's not to say he doesn't have a future in F1, but it is almost certainly too early for the Rouen-born racer, particularly given the fact that fellow teenager Verstappen will occupy the other car.
Gasly became a Red Bull junior after winning last year's Formula Renault 2.0 Eurocup. This season he stepped up to Formula Renault 3.5 and did a superb job, racking up eight podiums on his way to second in the standings. He has also contested a few GP2 races at Red Bull's behest.
The fact that he did not win a race this term suggests Gasly needs at least one more season at sub-F1 level, with either a second season of FR3.5 or a full-time switch to GP2 both possible. However it would be no surprise to see him appear in free practice at some stage next term, particularly if Vergne retains the STR seat.
Could Red Bull hire from outside their junior pool? It's all but impossible to imagine, but if they did choose to do so there'd be plenty of keen drivers. After all, this is a fully funded seat at a solid midfield team. Add in the fact they run Renault engines and it seems like a reasonable home for Romain Grosjean, while the likes of Kamui Kobayashi and perhaps even an ousted Kevin Magnussen could be tempted.
However it is so unlikely as to not merit discussion. Toro Rosso will field a Red Bull driver next year - unless Fernando Alonso runs out of options and offers his services, perhaps.
Vergne represents's Toro Rosso's most sensible option for 2015, albeit the less inspiring one. The Frenchman knows the team well and has three year's F1 experience to fall back on. That makes him the perfect foil for Verstappen, who will undoubtedly need a little direction during his rookie campaign. Sainz is the more exciting choice, but hiring him would negate that possibility.
This is not to downplay Carlos' abilities. He has shown this year that he deserves a crack at F1, but unfortunately circumstances have conspired against him on this occasion. Perhaps Red Bull can help find him a seat elsewhere in F1, then slot him in at Toro Rosso in 2016. However, for next term at least, they would be best served by retaining Vergne.