Increase range of hospitals able to transfer patients to.
Increase amount of requirements we're allowed to set for custom alliance missions so we can increase the difficulty and scale payout so we can make really difficult missions which only increase the payout a little bit but at least it would be something to bring the alliance together.
Of course there's a lot missing on the hospital and patient treatment side, as mentioned before by others, but I'm going to assume that's in the works and not bother adding to that list.
Hopefully my suggestions aren't crazy and I look forward to all the medicine related updates in the future.