I don't see the fit on D+. You're not going to draw fans into subbing to D+ to watch XFL games. Although I'm sure there is a lot of demographics that crossover with D+, it would make a ton more sense to put it on ESPN+. At least then, you're targeting sports fans, possibly adding value. Same amount of work and bandwidth regardless which streaming service they put it on.
Unless they plan to merge the products, I don't see the fit.