I think having a SureType keyboard (ex: Blackberry Pearl or the Nokia E55) would be an excellent addition if you guys come out with a 2nd edition. It’s easier to type with and could work with the current design of the phone.
Call Blocking is a must. A lot of spam calls in the USA and elsewhere. Having the ability to block calls and text messages would be wonderful.
Also maybe an appstore would be a great addition if things go extremely well. It would let users decide how much connectivity do they need. Maybe they need a minimal phone that can also do Uber, for example.