You misunderstand, I am saying 360 and PS3 did fine with the PS2 pricecuts during their reign. But XB1 and PS4 late gen sales may suffer since last gen never got pricecuts. People who adopt consoles or 2nd consoles late, may never have done that with 360 and PS3 and then those people bought XB1 and PS4. Which leads to inflated early gen sales and a short tail end. Brand awareness will then suffer for next gen PS5.
Of course the dynamics of PS4 neo and NX will probably change these thoughts as well.
I don't think there's any causal link between late-gen price cuts for older systems and sales performance of their next-gen counterparts. In fact, I've never seen a case where anything having to do with an older system had any bearing on the sales of a newer system. Now newer systems do have an effect on older systems, as once the new system is release the system it is replacing typically experiences a sudden drop in sales. The main reason PS3 & 360 sales had such a late peak had nothing to do with PS2 or Xbox sales and everything to do with factors specific to the 7th generation. Likewise, there nothing in the sales data to suggest that the pricing of the 360 & PS3 will have any bearing on the future performance of the PS4 & XBO.