I don't even know why I take your baits anymore, but let's see...
There is no reason at all to end Shokugeki no Soma after this arc, it is the opposite, the sales are good and the ranking is also good most of the time. I don't even have to talk plot-wise. Talking about the anime, I don't know what you are talking about since we have 10 whole volumes + a bunch of still not collected in volume chapters separating the end of the second season of the current chapter. We have the Moon Banquet Festival Arc before Central arc, which was great. This arc occupies 3 volumes and can last a half-dozen of anime episodes or more. Then we have Central arc, which had some good duels and a lot of additions to the plot. I don't focus on the general complain that Azami is a bad villain and instead I enjoy what is happening in the story despite that. This arc can lead to more 10 episodes or so, they can even finish the season before the Hokkaido arc given the amount of material they already have in these two first arcs. I think it will not be possible to comprise these two arcs, plus the Hokkaido arc in a season of 25 episodes and we don't even know whether we are going to have a 25 episodes (I think it is probable, but we never know). Therefore, they are really fine with the amount of material, it is not even close.
This argument that the manga sales will fall with the anime is the most ridiculous I've ever heard. People who are buying the manga right now already know what will happen in the anime and if they didn't give up of the manga then, they are not going to give up now.
Great, if you don't expect anything from the series, I suggest you to keep quiet and go read Dr. Stone.