My iPhone 5S was stolen and I used Find My iPhone App to remote wipe it. Can someone still jailbreak that phone and use it as a new phone?
Since iOS 7, Apple has employed Activation Lock. Once Find my iPhone has been enabled, the device is bound to the user's Apple ID and will require the username and password of that particular Apple ID to restore or activate.
Remote wipes put a lock on the device on top of clearing out the data. Once that phone is turned back on, a password will be required.
Activation Lock cripples iPhones for life (or till the user enters the Apple ID password).
The thief that has your device now has a brick and it will always be a brick. There is absolutely no bypassing Activation Lock because Apple's servers will chase it forever.
The only procedure left to the thief is to put the device in DFU mode, but once the restore is complete, the user will again be prompted for the Apple ID password upon setup. And since the device checks Apple's servers for this hold, the thief is left up a creak.
You can see on Apple's website what Activation Lock consists of:
With Activation Lock, your Apple ID and password are required before anyone can:
Turn off Find My iPhone on your device
Sign out of iCloud on your device
Erase and reactivate your device
Jailbreaking a device requires access to it. If it was that easy, Activation Lock would be useless. Apple is much smarter than that.
iPhone Hacks has a more in-depth look at the feature: Protect your iPhone against theft with Activation Lock
Physical Access is Total Control. This is the 100% truth on all things computing.
As soon as your phone is physically in someone else's hands, if the thief knows what they're doing they can get around anything.
I won't go into detail about how they can subvert a remote wipe, or more generally gain any level of access to your phone, but it's fairly straight forward and the feature exists on literally every single iPhone. (And I think identically even iPod Touch and iPad.)
The part of this I do NOT know the answer to, is the recent carrier activation security feature ( http://www.huffingtonpost.com/2013/06/10/phone-theft-activation-lock-apple-_n_3417032.html ). I believe the intended effect of this is that the thief would never be able to activate the phone with a cell service when the phone is wiped, in essence, reported lost/stolen.
While they may not be able to activate the phone, they can still gain access and read your data, assuming they took the phone offline before the Remote Wipe could take effect.