If it really is easier to develop for than the PS4 then that should mean it is cheaper than porting to the XB1.
As long as the Switch has healthy sales similar to the post price cut 3DS then they'll get ports.
but one thing is develop for switch, to my understanding, and another is porting. Porting means compromises to an already existing product. Developing for means making the product tailored to a certain HW. And like it or not, that usually doesn't happen with 3rd parties. So the easy thing is develop for XBO/PS4, and downgrade. ANd we know how that ends.