With Daniel Ricciardo's exit from Red Bull confirmed, many are casting an eye along the grid looking for likely contenders to fill his race seat in 2019. Here's a look at some of the leading candidates.
Carlos Sainz — On paper, Sainz is the form driver, and should be the leading contender to line-up alongside Verstappen next year. It's ironic, though, that his history with Verstappen could actually count against him. Although Verstappen showed fantastic promise and explosive over-taking potential at Toro Rosso, most critics agree that Sainz was almost his equal on performance. Their squabbles in the Red Bull Jr team could be put aside, with much of the animosity stemming from a desire to be elevated to the "senior" team. With that accomplished, the pairing just might work.
Pierre Gasly — The frenchman will very likely be the front runner, with not only notable performances this season, but experience with Honda powered cars. With the Red Bull Honda partnership still something of an unknown (could it have been the final straw behind Ricciardo's exit?), this unique advantage, and the fact that Red Bull love promoting their youngest stars, will give him an edge on the rest of the field.
Brendon Hartley — The only other driver with experience at the helm of a Red Bull + Honda powered car, yet rumours than Hartley might not even see out the summer would suggest he's not in serious contention. With a senior driver pulled from Red Bull's ranks, it might however mean an extension to his career with Toro Rosso.
Esteban Ocon — On loan to Force India from Mercedes, Ocon was supposedly lined up for a move to Renault next year, but with Hulkenberg and Ricciardo now confirmed, it appears that ship has sailed. Rumors that Lawrence Stroll could snatch up Force India and, presumably, install his son Lance alongside Sergio Perez, Ocon needs a solid mid-field seat to sustain the momentum he has already achieved in Formula 1. If he shines in the next month or two, and Sainz and Gasly underperform, Toto Wolff might just be making some phone calls.
Kimi Raikkonen — With Charles Leclerc looking certain for a move to Ferrari (although, who really knows anything anymore?) Kimi Raikkonen is presumably free to change teams as he pleases. For the Finn, the most likely course of action will be retirement, unless Haas or Williams decide to pick up the laid-back former world champion, and he decides to grace F1 with his company for a little longer. Red Bull has always instilled the winning culture in their drivers, and prefer to nurture their own talent than recruit from outside, but as Kimi showed when he returned to the team that sacked him, stranger things have happened.
Lando Norris — Red Bull put in a request for Norris when they were looking for a ringer to fill their Toro Rosso seat last year. They were told the McLaren reserve driver was off-limits at the time, and at best he might be released to drive for the Junior team, with a call-up to Red Bull in his rookie year probably too much of a stretch.
Fernando Alonso — There is no man who has more talent and a less certain future than Alonso. Although his motivation has been tested in recent years, he still out-performs his car most weekends, and surely the hope of one last world title would be tempting enough for him to sit down with Red Bull management to discuss the possibilities. In the short-term, if the Red Bull chassis can compensate for any Honda short-comings, it's possible that a Versteppen-Alonso pairing could provide the fuel for an explosive charge on the constructors' championship, should Mercedes or Ferrari let their foot off the gas. How happy Honda would be about a reunion with their most vocal critic? Well, let's say they'd probably be less than pleased.
Ricciardo's move has triggered a number of reactions in the driver market, just as it did when Vettel announced he was leaving Red Bull to join Ferrari, or Nico Rosberg did when announcing his shock retirement in 2016. Who capitalises, and who sets themselves up for glory beyond 2020 when the new technical regulations are brought in, we shall have to wait patiently and see.