Like it has been said already, CoD games have been going down sales wise. Meanwhile, Pokemon has the potential to go beyond that. I believe the Switch title will sell better than even Blue and Red. I don't have indicators of it perse, only that a craze like Pokemon Go brings me to that conclusion. I don't know if it can hold it like GTA V and keep selling. However, It is not wise to expect Pokemon to sit like that. Especially not at 13.6m when it does.
Well that's a very different from "Unless no Pokemon games get released ever" xD
Sales for CoD were going down, WW2 has done very well and sits at around 17m currently (vgc for ps4+xbo, steam spy for pc) and will surpass the 19m average.
I don't think that Pokemon on the Switch will sell 30m+ but even if it did, it's not an annual release, so Call of Duty can easily surpass that over two entries. Even releasing a 30m seller every 2 years isn't enough.
For CoD to not pass it, requires both Pokemon sales to increase by 50% from the 3ds, and CoD to decline. Which seems less likely than not.