FBI: International could definitely mean change for NCIS’ future, if indeed NCIS does have a future beyond 2021.
It is worth noting that FBI: International, which will follow the elite agents of the FBI’s International division as they travel the world with the mission of protecting Americans, presumably won’t have as many opportunities for crossover as the U.S.-based FBI and Most Wanted, however.
Personally, I think that CBS is going to group the three FBI shows on one night, even if that means NCIS ending, or either CBS moving NCIS or finding a new slot for two returning shows and one freshman series rather than just the one.