Probably will happen. 3 years for a mid-gen refresh a good compromise between the smartphone model and the old hardware model of 5 year cycles.
Everyone who said PS4 Pro and XBox One X would be terrible and splinter the market and blah, blah, blah were wrong. Both have been well received and give the consumer more options and Sony and MS take home higher profit margins off these higher end models.
It's win-win for everyone.
Nintendo has already been doing this with their portables anyway, New 3DS came out 3 1/2 years after 3DS with a more powerful CPU + a lot more RAM and there are several games that take advantage of that, this is just the next natural progression.
Switch Pro in 2020 that has PS4/XB1 tier performance (or optional performance increases for existing Switch games) would do very well.







