The England international is now third choice in the Gunners' centre-forward ranks behind Kai Havertz and Gabriel Jesus and is expected to be sold for the right price this summer.
A handful of Premier League teams, including Brentford and Crystal Palace, have been linked with Nketiah, but he is also believed to be open to trying out a different league.
Marseille, who have already poached Mason Greenwood from Manchester United, are thought to be at the head of the queue to sign Nketiah, who could follow a host of ex-Arsenal men to the Orange Velodrome.
The likes of Sead Kolasinac, Nuno Tavares, Alexis Sanchez and Matteo Guendouzi have all represented Marseille since leaving Arsenal, as has Pierre-Emerick Aubameyang, who left after one season to join Saudi Pro League side Al-Qadsiah.
Arsenal 'likely to reject' second Nketiah bid
Nketiah could therefore arrive as a direct replacement for ex-teammate Aubameyang in the number nine slot, and according to The Athletic, Marseille have now submitted a fresh bid.
The proposal would apparently see Arsenal receive around €20m (£16.9m) for their Hale End product, which is not a million miles away from the first offer that Marseille lodged, but with a different payment structure.
However, the report adds that Arsenal are still expected to reject the offer, which falls well short of their asking price for the 25-year-old, believed to be a club-record £40m.
Marseille and Arsenal remain locked in discussions as the French outfit try to find common ground with their North London counterparts, whose record sale remains Alex Oxlade-Chamberlain's £35m Liverpool move in 2017.
Nketiah has apparently given the thumbs-up to a five-year contract with Roberto De Zerbi's team, although he still has three years left to run on his Arsenal contract, which he last extended in 2022.
Is Nketiah worth £40m?
In spite of Arsenal's monumental progression on the field, the North London giants' inability to recoup suitable fees through player sales remains a major bugbear for many Gooners.
Mikel Arteta inherited an ageing, disunited squad where contract terminations were common practice, and Arsenal have continued to accept lowball offers simply to rid themselves of the deadwood.
However, the Gunners can now afford to drive harder bargains, especially when it comes to relatively young, home-grown players in the middle of a long-term contract, as is the case with Nketiah.
The 25-year-old boasts a respectable 38 goals from 168 games in an Arsenal shirt and has often stepped up to the plate when injuries have taken their toll, showcasing his quality when he knows he will be a guaranteed starter.
If Fulham are happy to pay a total of £34m for Emile Smith Rowe, who has had even less of an impact over the past two years, £40m for Nketiah has to go down as a fair price.