Now, I'm no expert here, but I'm wondering if this bill, like most bills is dated for effect Jan 1 2015, after its signed?
I know usually when the Pres signs a bill into law at the end of the year like this the law often doesn't go into effect until the 1st of the new year. This is the case for example with the zany health care laws Obama signed into law. Most did not take effect immediately, in fact some are still pending, even though signed into law.
If the President doesn't sign the bill within the 10 required days, it'll still become law, again on the effect date as long as he doesn't return it to congress and congress remains in session.
However if the President fails to sign the bill for some reason over the next 6 or 7 days (now, was 10) and doesn't return it to congress (veto) BUT congress adjourns during the 10 days (which with Christmas is possible) then the bill does NOT become law. This is known as a "pocket veto".
So if he doesn't sign for whatever reason and congress goes home for Christmas vacation, then the bill just got pocket vetoed (basically vetoed out of neglect)
Now I'm not sure on this bill, I haven't read it all but its possible that it wont' go into effect until Jan 1st of 2015 unless someone has information that shows it has no start date and is scheduled to go into immediate effect.