Having physical disconnect switches (Bluetooth/Wifi, Modem, Power, Microphone/Speaker), and integrated lens cover like Lenovo laptops (at least for the front camera whereas a case can cover the rear cameras).
On a side-note:
Triple active SIM would be amazing, but one can dream. I would love to have a phone that has an active AT&T, T-Mobile, and Verizon SIM at the same time.