You know what us, experienced people want? Lances, Dragon knights, and Dragon Kings. Maybe 1 new gamerule but we want pieces, not these stuff. Also a 5th player to act as bots or bounty pieces. Maybe even a player for a potential 5P Variant!
We will practically need extra long-range pieces with extra squares, but we currently need more interesting “weak” pieces than just the General .
so why not only leave ferz,wazir,daddaba,alfil,knight and camel to "merge" piece(merge FF,ferz-rider,is a bishop,etc.)