I think the obvious answer here is not something that you clip to your phone but rather your phone itself. I foresee Dexcom switching to low energy bluetooth for the transmitter. This was specifically targeted to the healthcare industry.
Dexcom could still make a proprietary receiver but bluetooth would open up the ability to run the receiver software on an iPhone, iPod touch, or Android phone. It would also be possible to have a bluetooth wristwatch version. As a software developer this excites me because it would enable me to address what I see are many shortcomings in the current receiver. All of these would be very easy to implement in software:
Predictive alerts (warn if you will soon be high or low)
More alarm flexibility (like phone profiles - only beep between certain hours, etc.)
More alert options. What if I want 75 to 115 during the day and 70 to 130 at night?
The ability to always see my current BG when an alarm goes off. Don’t make me snooze it for 30 minutes just to see the actual number.
Configurable graph - likes others have mentioned I don’t need it to go to 400.
Ability to view more than 24 hours of history and see the actual data, not just a graph.
View events like insulin and carbs.
Enter/edit events after the fact.