Current speculation around the raising of flaps suggests that independent engine failures weren't the cause. Proper investigation with access to better data than grainy video will tell us if that is the case and why.

"4 smaller but equally efficient engines" feels like a unicorn though (we'll probably get to the point in future where four large engines are superior in efficiency to two of today's engines, but two large engines to that latest design will still be more efficient than four smaller ones...)