Well, it depends on how it’s done.
If they are just gonna remove the tax exemption on airplanes (they should… and don’t forget private ones too!) without in turn making the train and other greener alternatives exempt of taxes… then that’s not really encouraging the use of the train, but just making the cost of travel higher overall.

It makes no sense to me how sometimes even the cost of the gas for driving a private car to cross the country is cheaper than doing the same via a public transport like the train…