In that xcase Poland as ally of France will stay neutral and only grab Teschin area in case German occupation of area is close. Actually this may even happen in cooperation with Czechoslovak army.
Perhaps a coup by Radola Gajda's fascists or an uprising by the Slovaks (or perhaps both, with the latter being caused by the former) could lead Poland to decide to take advantage of the disorder in Czechoslovakia and maybe in support of the Slovaks.