Capot, you are late there have already been arrests for using 'model aircraft' to attack various targets:
Man, 26, charged in plot to bomb Pentagon using model airplane - CNN.com
and
Moroccan man 'planned to fly model planes packed with bombs into school' | Daily Mail Online
These of course are fixed targets and therefore far simpler than attempting to hit an airliner which is actually surprisingly difficult with a UAS that is probably capable of less than 25% of the speed of an aircraft on approach. I think that such collisions are more likely to be accidental.
There are RTCA and EASA working groups developing requirements for management of UAS and for DAA and the associated datalink requirements for BLOS and control operations. Research is also in hand on how to integrate UAS into the National Airspace System. To some extent SESAR is a little more advanced as the individual countries within ECAC (European Civil Aviation Conference) that is the states that within EUROCONTROL - are all making independent approaches to UAS.
Generally the UAS seem to be falling into 3 groups:
* Large 'toys' being used for fun or low grade commercial purposes
* UAS under 55 pounds that are used for professional or 'state' purposes
* UAS above 55 pounds all the way up to full sized aircraft a UAS conversion of the F16, Global Hawk and many many others.
The problem area is the 'large toys'. Especially now the media have got involved publicizing them and the manufacturing of them is so cheap and easy. The last two groups will follow all the regulations, the first group will be flown by some who do not even know such regulations exist and wouldn't care even if they were told.
Anyone who thinks this is going to be an easy area to regulate just has not been involved with what is going on. Professionals in the small UAS group below 55 pounds are extremely concerned that they will be regulated out of the market due to the actions of the large-toy group of idiots.