A some one who's maintenance engineers licence covers a range of composite aircraft I fail to see how this aircraft will be any more of a problem in terms of risk to passengers involved in an accident that aa aircraft of convetional construction, in fact the ability of composites to absorb energy may well be an advantage keeping the structure intact and allowing more people to escape before the (undoubtedly toxic) fire gets going.
For me the main promlems that I forsee are ones of maintenance. Boeing repair manuals are using "dark ages" methodes that would not be used on any light aircraft or glider and are not fit for primery structure due to the glued contact area between the layers of cloth being so small. these practises may well be satisfactory for floor boards and non critical panels but won't do for a pressure hull.
I have no doubt that Boeing have given this much consideration but will an industry that has for so long been wedded to metal put enough effort into re-traininng staff to repair and inspect these "new " structures that are so much better at hiding defects and dammage than metal ever was!