2H2O right arrow H3O+ + OH-
Is an endothermic reaction. If you increase the temperature energy is added to the system according to Le chatelier the system would partially oppose the change by removing the excess. Hence going in the endothermic direction (net forward)
equilibrium lies to the right not left
This would increase the concentration of H30+ and OH- by same amounts.
The PH would fall because there is more H30+
The solution is still neutral though because eventhough the PH falls there is also a new water constant. It is no longer 10^-14. At this new constant this PH is considered neutral.
Obviously the concentration H3O+ = OH- also. Further proof it is neutral.
Hope this helps