You find folk get stressed over this as to they want to buy what's out now and worry a new model is going to come out.
As to security, why do you think it's secure? For example you can dump a locked Apple iPhone with any of the forensic boxes or tools listed at http://www.forensicswiki.org/wiki/Apple_iPhone
Again, why would thumb impression help?
There are rumours that iPhone 5S or iPhone 6 (whatever it will be called) will be introduced in a number of colours, with big size, excellent 12 MP camera, thumb impression detection for security and will be a bit bigger in size.
What will be your favourite feature among these new inclusions?