I had the exact same thought when I heard all the modes coming.
Having too many gamemodes available at once will lead to too much dispersion of the players. In the beginning when the player peak is high this should not be an issue, but over time we might see the same as currently is happening in BF2042 time limited events that feature a specific mode. As long as they keep the franchise staple modes available at all times, so Conquest64, Breakthrough, Rush and TDM, ok and to please Sawtooth75 Domination (quite a fan of that too myself tbh).
I also hope that if the population starts to decrease they will lower the player to start count on all modes to avoid wasting time waiting for servers to fill up.
Best remedy to avoid a decreasing population would be to launch a proper Battlefield that regains and maintains its community.