3-10 in 2015 has 2 elite star wingers, 2 top-pairing defenceman (one you clearly covet), and the rest are competent top 9 or top 4 defenders. I think you are dramatically overestimating the hit rates of draft picks. 2015 at this point had multiple people in the 3-10 range making a sizable impact on the NHL. Honestly, look at what people thought of Hanifin, Zacha and Strome in spring of 2017. You are dramatically overestimating the cumulative odds of multiple of these guys hitting to the extent you get better then 2 star wingers and 2 top pairing defencemen who are still 24 or younger.
Yeah it's pretty unlikely that all of Byram, Seider and Broberg top out as top 4 defencemen. Then you need at least two of Dach, Turcotte, Cozens, and Zegras to be better than Marner/Rantanen. And all of the entire 3-10 range to at the very least be top 9 forwards and top 4 defencemen to even have a chance to match 2015. Strome, Zacha, Meier are at the very least middle 6 players.
Just playing the odds it's likely at least 1 player busts in that 3-10 range in 2019.