Never say never, but the odds are minimal. The 20 ships are especially designed to trade on two weekly service loops between the Far East and Europe.
However: These 18,000 teu ships as well as CMA CGM's and MSC's 16,000 teu ships will eventually replace vessels of ca. 13,000 teu. Through cascading effects, the introduction of 16,000 to 18,000 teu ships on the largest tradelanes (Asia-Europe) will eventually see further ships in the size range of 8,000 to 10,000 teu (and maybe even the first 13,000 teu ships) to enter the trade between Asia and the USEC/USWC.