IDK about the neo....but its likely the present 320 family shares similar compromises. Both the 900 and 320 are matured variants, grown near to the practical limits of the base design. With the exception of the AB capacity to accept newer engine technology.

But more efficient engines are only a part solution, the other part being necessary increase in thrust class to support the airframe growth variant.

If the CFM had the growth capacity to achieve a 40+K thrust class it may solve the problem. IDK.....maybe a 'reheat' system for TO would do the trick..