Boeing has explored a similar concept and may still be doing so. At least two major problems are evacuation times and airport design of ramps and jetways.
Instead of worrying about making a green passenger jet they should work on cost effective super sonic one. It would be nice to get to across the pond in four hours.
Yes, the Boeing X-48 scale design UAV, first flight OVER 13 YEARS AGO.
There's also the pesky matter of just where those overhead jet engines go in the event of a hard landing or mount failure. As currently configured, having them crash thru the fuselage would make for a Very Bad Day.