By how much ? In 2019 the X costs 500 bucks. Let's suppose next-gen arrives in 2020 (the most possible option). What will be the discount in a year ? 200 hundred dollars, so they will sell it for 300 ? Seems unrealistic to me.
While Sony will sell ps4 for 200, Microsoft will kill it's main competitor, One S. This also seems unrealistic to me.
I do find logic in Sony moves (let's say slim for 200 bucks, pro for 300, ps5 for 500 bucks in 2020), but i don't see how Microsoft will fit in the market all 5 consoles, going by the rumours. Xbox One S, X, Lockhart, Anaconda and that streaming box. KIlling the first two doesn't sound like a good idea at all.