Ferrari have begun the search for a new team principal after the Scuderia announced Mattia Binotto had handed in his resignation.
Said to be case of jump rather than be pushed, the 53-year-old Italian paid the price for Ferrari's error-strewn 2022 championship in which they saw a 46-point advantage overturned by Red Bull and Max Verstappen who romped to the championship double.
Charles Leclerc was a distant runner-up with Ferrari second in the Constructors' Championship. But as former Ferrari team boss Stefano Domenicali said: "When you are second for Ferrari it is something that is not enough."
Horner was asked by Sky Sports to weigh in on Binotto's exit, telling the Craig Slater he was "not really" surprised to hear the news.
"It is obviously Ferrari's choice," he added. "I think it will be the sixth team principal I have sat opposite since I've been at Red Bull.
"Obviously difficult for him. They had a great car this year, they were very competitive."
Since 2005 when Horner was named team boss at Red Bull, Ferrari have had Jean Todt, Domenicali, Marco Mattiacci, Maurizio Arrivabene and Binotto at the helm.
According to reports they are now keen on Alfa Romeo team principal Fred Vasseur taking over from Binotto, having previously knocked on Horner's door.
Asked about speculation Ferrari came calling last winter already, Horner did not confirm or deny that, saying: "My commitment is very much with the Red Bull team. I've been there since the beginning and have a very close attachment."
Christian Horner predicts a 'really tough season next year'
This season it was all Red Bull in both championships, at least it was after the team resolved their early season reliability woes that saw Verstappen record two retirements in the first three races.
The reigning World Champion raced to 15 wins in the 22-race season, a new record for the most wins in a single season, and scored 454 to take the title by 146 points.
But with Mercedes showing huge improvements in the latter part of the season, Horner reckons Red Bull will have a tougher time of it next year.
"I think both those guys had great seasons," he said of the Mercedes team-mates George Russell and Lewis Hamilton.
"George finishing ahead of Lewis in his first year with the team was an impressive performance but Lewis is obviously still right there.
"You've got to assume they're going to come back fighting hard next year, Ferrari as well will be looking to make progress.
So, it's set to be a really tough season next year."
A two-pronged budget cap penalty
Winning this year's Constructors' Championship means Red Bull are limited in next season's research and development time, F1's aerodynamic testing restrictions handicapping them to the tune of 70 per cent with the team that finished bottom of the log, Williams, permitted 115 per cent of the allowance.
But Red Bull's penalty for breaking the budget cap means a further 10 per cent reduction, leaving them with just 63 percent. That equates to 202 runs in the wind tunnel to Ferrari's 240 and Mercedes' 256.
Horner reckons the "draconian" penalty will cost the World Champs anything from 0.2s per lap to as much as half a second. That's a number that rivals have of course downplayed.
It is, however, now being suggested that while Red Bull won't feel the full impact of the penalty next season, a lot of work having already gone into next year's car, they will in 2024.
The Milton Keynes squad will need to balance working on upgrades for next year's RB19 versus improving their 2024 RB20, and they will have to do so with limited R&D compared to their rivals.
While Red Bull will be short on time, Mercedes and Ferrari will have extra and even more now because of the penalty. It is effectively a two-pronged punishment.