Mid-Gen refreshes have been a huge success IMO. XBox One being double this year and on track for its best year ever is mainly due to XBox One X.
PS4 not seeing the usual decline you would expect to see in a system in year 5 IMO also points to PS4 Pro helping offset usual hardware fatigue.
People who said this idea wouldn't work, would splinter the market, wouldn't sell, etc. were wrong.