How many coaches will the new Flourish station be able to hold?
If there were to be a new arena built in the Bay, then consideration will likely be given to event planning and similar setups to Central on Stadium days would be drawn up, so basically some kind of queueing system. With regular trains going up and back to Queen St / Central, it won't take long to clear the queues if in a minimum 4 coach formation.
What there is then a risk of is shifting too many people at one go into Queen St or Central and having no opportunity to queue people outside without forcing people back outside after arriving and into another queue. That could lead to overcrowding on the platforms, especially at Queen St where space is limited.
The good thing is that by the time any new arena is built, the fleet situation will be in a much better place, with greater flexibility and more capacity available.