Toro Rosso are an odd team. They do not aim to succeed as such, but rather to develop young drivers so that they are capable of moving on to the senior Red Bull squad. There can be no thoughts of long-term progress, because the best will always leave. And a solid experienced driver is no good either, because what use are they to the main team? It is a unique dynamic for an F1 operation.
So what of their lineup for 2015? Assuming there are no changes at Red Bull, Daniil Kvyat's seat is almost certainly safe for next year. The Russian has impressed with his rapid adaptation to F1, particularly by scoring points in his first two grands prix.
He's been less eye-catching since, but that is partly down to the Toro Rosso's habit of breaking down. Red Bull team principal Christian Horner recently went on record with praise for Kvyat, suggesting that the team's decision-makers are pleased with his progress.
It is a very different story for his team-mate Jean-Eric Vergne. The Frenchman is now in his third full season at Toro Rosso and, by the campaign's end, will have contested more races for the Faenza-based outfit than any other driver. However he's unlikely to extend that record into 2015, as this is likely to be his last year at the team - and possibly in F1.
He's not doing a bad job. In fact, the Toro Rosso hierarchy are often quick to praise JEV for his work and how it benefits young Kvyat. It should also be noted that Vergne was regularly able to match Daniel Ricciardo last season, especially on race pace, which appears all the more impressive in light of the Australian's performances at the senior team.
But despite this the Frenchman is not seen as a Red Bull driver of the future, while Kvyat is. And at a team designed solely to nurture budding talent, Vergne is getting a little long in the tooth - he'll be a grand old 25 next season - while a pair of younger drivers have an eye on his seat.
So let's assume Vergne is pensioned off at the season's end. Where does he go, and who do the team replace him with?
JEV has two options should he split from Toro Rosso. Given his work for the team and the praise he's earned, Red Bull are likely to offer him a new deal which would include some F1 testing and demo-run work. That would mean job security - vital in the current motorsport climate - and would allow Vergne to find a seat in another series. Just look how well Sebastien Buemi has done in very similar circumstances: the Swiss racer now has a factory Toyota drive in the WEC and a plum seat with Alain Prost's Formula E squad.
Or he could follow the path of Buemi's former Toro Rosso team-mate, Jaime Alguersuari, by leaving Red Bull altogether and chasing another F1 berth. In Alguersuari's case this didn't come to pass, and for Vergne it looks an equally big ask: who is going to hire a solid-but-unspectacular Frenchman with no financial backing?
Another option would be to make his case to the Haas Formula team which will debut in 2016. They have stated that they'll run one experienced F1 campaigner and one young American when they arrive in the sport. Vergne fits that profile nicely and, if he did land the seat, would still be only 26 when he resumed his full-time F1 career.
As for Vergne's replacement, there are two candidates at present. 19-year-old Carlos Sainz Jr. is currently favourite for the role. The son of two-time World Rally Champion Carlos Sainz Sr., the Spaniard currently leads the Formula Renault 3.5 championship by a healthy 39 points with three rounds remaining.
He already has F1 experience thanks to testing runs for both Red Bull and Toro Rosso, and his nationality and family ties make him appealing to the team's Spanish sponsor Cespa. Hiring Sainz would also mean recreating a familiar driver lineup: he and Kvyat have already been team-mates in Formula BMW (2010), Formula Renault Eurocup (2011) and GP3 (2013).
Also in contention is 2013 Macau Grand Prix winner Alex Lynn, who currently leads the GP3 standings in his rookie campaign. If the 20-year-old can win the category he will have a very strong case for an F1 drive, though with Sainz a step ahead of him career-wise Red Bull may opt to place Lynn in FR3.5 - most likely in Sainz's old seat - while building his F1 experience in free practice and testing.
The team have also been linked with Max Verstappen, but the chances of them throwing him into F1 aged just 17 and fresh from Formula 3 is too ludicrous to contemplate. If Max does align himself with Red Bull, expect him to step up to GP3 or FR3.5 first.
Ultimately, Toro Rosso's driver dilemma is a pleasant one. Do they drop the solid, experienced Vergne and replace him with Formula Renault 3.5 standout Sainz? Or could they draft in Lynn, reigning Macau Grand Prix winner and star of GP3? The term 'embarrassment of riches' springs to mind.
VERDICT: Kvyat and Sainz Jr.