Well Unreal is based on java style design, and as such is slow, bloated, and hard to maintain(mountains of code, where each line does as little as possible).
Moving away from Unreal style engines would be a first step.
Also games that use the same engine seem very 'same same' to me, greatly reducing their appeal...
-Moving content creation to users
-removing the endless hacks
-engines that scale to near 100% hardware utilization on whichever platform they happen to be running on
-turing complete game worlds
-original visual designs, not just replicating reality