Can you replace whole eggs with only egg whites when baking pumpkin pie?
Pumpkin pie is basically a custard, removing the yolks could change the texture of the pie.  Yolks contribute both proteins and fats to the pie which are important for the structure of the filling as well as its creaminess/smoothness.  In general, two whites can be used to replace one whole egg.  Avoid whipping or over-mixing the filling to prevent making the custard rubbery.Be sure not to overcook the pie, without the yolks there to emulsify the filling and lubricate the protein bundles, you could end up with a dry, curdled mess.