03 Mazda 6 Cylinder coils

[snow1813]

I purchased a used 03 6, with 30,000 or so miles on it back in Nov. 04. I haven't had any problems until recently, and was wondering if anyone could share their knowledge. In the last 7 weeks, I have had my car in for repair 3 times due to the check engine light coming on. The first repair was for the throttle body, the second time there was a collapsed hose, and this last time it was a bad cylinder coil. The guy at the dealership told me that he cannot guarantee that the other 5 will not go out in the near future.
Two questions-1) What is the likelihood of that happening? 2) What else can go wrong, given the entire series of events?
Please keep in mind that I am definately not a car chic!
Thank you in advance