Can thieves get around Find My iPhone in the iOS 7 version?

Question

Yesterday at the Seahawks game my 5S (32gb, gold) fell out of my pocket when I was jumping like crazy during a Marshawn Lynch touchdown. Someone right next to us picked it up and turned it off right away. My husband immediately put it into "stolen" mode in Find My iPhone, and it had been maybe 10 minutes at the most since it fell out of my pocket.
We did all the right stuff--that phone won't work on the AT&T network at all, we keep checking in with security to see if someone it was left in the stadium, the Seattle PD has an open case, and Apple has the relevant info with the serial number and such. It had a passcode lock plus my fingerprint ID in use.
Unfortunately, the thief still hasn't turned it back on. And I've tried researching but wanted to see if you smart people have any insight here--is there a way someone can still get around this? Like, is there a sophisticated way they could jam the cell signal, not turn on wifi, and somehow break into the phone and jailbreak it or whatever? Or is there hardwired means that the serial number or whatever Apple accesses to ID it as a stolen device just can't be overcome?
Basically, I REALLY hope that it's a brick with absolutely no way to overcome it and by some miracle the phone gets turned in. Our son, who is almost 3, has autism and doesn't speak. The other day he started pointing out letters to me and saying them and it was such a beautiful moment and I grabbed my phone and got it on video, plus I got some cool videos of the actual Seahawks game. We're HUGE fans and only go about once a year. So I'd really love to, by some miracle, get those back.
BUT if I can't get the phone back, ever, I REALLY just want the peace of mind that it's an unusable brick and there's no way that some ahole out there is going around using my phone, nor that they were able to make it usable and sell it and some unknowing person paid $600 and now gets to use my stolen phone.
Anyway, when I called Apple the guy said there's no way that phone can ever be used, no matter what, unless they put in our Apple ID and password, and that it is completely impossible to break into the software and wipe it without accessing the internet, which means we would immediately get the location notification. Even the police officer who took my report said she doesn't understand why people steal iPhones because they are complete bricks and there's no way around it. Still, I just feel like if that were true people wouldn't keep stealing iPhones.
So do any of you have any insight? Thanks for entertainging my obsessing over this shat situation.

Answer 1

I should clarify: I didn't know it fell out, but I check my phone often enough that there were only about 10 minutes between when I last put it in my pocket and then realized it wasn't there.
We asked everyone around us if they saw it, and like 10 people were helping us look. But my husband used Find My iPhone and the Prey app right away when we realized it was missing (again, at most 15 minutes from the last time I used it) and it was already in offline / "cannot locate" mode.