Broncos and Storm are certainly looking good to make the top 8. A few more wins and missing the top 4 would be unlikely.
But great as they are going, once you are in the top 4 you need 2 wins to make the GF and 3 to win the premiership, likely all against other teams in good form. That is tough to do, and accounts for the variety of premiership winners we have seen over the last decade or so, and the lack of back to back winners, even when a team dominates the regular season for a few years.
Lets say you rate the Storm an 75% probability to win each of their finals games (a very high probability vs other good teams in knock out pressure- very few teams win 75% of their finals over a couple of years period, even when doing well in the season), that would still mean they are less than an even chance to win the premiership (75% x 75% x 75% = (just over) 42% ).
And obviously that would mean you don't rate the Broncos such a high % to win all 3.
And if you rated Broncos a 75% probability to win their games up to the GF, when they don't play the Storm, and have the Storm and Broncos 1 and 2 on the ladder, they still have only about a 30% probability of meeting in the GF. It is the nature of tough knockout competition- it is difficult to be certain of results even if a team is in good form and winning most of its games.