A possible counterargument to 12×12 being too much for a ‘standard’ might be Chu Shōgi — after all, it was the most popular Chess in Japan before the introduction of drops to its smaller brother.
I'd expect a ‘Next Chess’ would be likely to at least have a single set of basic rules (i.e. regarding check, promotion, winning conditions, ⁊c.), probably the FIDE ones, though arguably even there there is some tweaking that might be worth doing; I would be very much in favour, though, of a poker‐like situation where multiple games (probably just different piece sets, in practice) enjoyed comparable popularity — and might even be mixed regularly in both casual and tournament play.
A possible counterargument to 12×12 being too much for a ‘standard’ might be Chu Shōgi — after all, it was the most popular Chess in Japan before the introduction of drops to its smaller brother.
I'd expect a ‘Next Chess’ would be likely to at least have a single set of basic rules (i.e. regarding check, promotion, winning conditions, ⁊c.), probably the FIDE ones, though arguably even there there is some tweaking that might be worth doing; I would be very much in favour, though, of a poker‐like situation where multiple games (probably just different piece sets, in practice) enjoyed comparable popularity — and might even be mixed regularly in both casual and tournament play.