Doncaster, Rochdale, Keighley, Swinton, Whitehaven, Barrow, Crusaders and Workington are also in the upward mobility club so that's 10 out of 14. That;s quite a turnover and this season we will lose five so the division is quite different to the sustained dominance of Leeds, Saints, Wigan and Warrington in SL and the rest retaining their status quo year in year . The only drop outs from the top tier dominance have been Bradford.
And the only new entrants are Huddersfield and Warrington. Go back to the 2000s or the late 90s and the names on the trophies are almost exactly the same as now (barring the odd Hull FC win). Go forward to the 2020s and probably won't be much different.
With the lower leagues in the same time frame you would see wins by sides like Keighley, Castleford, Salford, Hull, Hunslet, Dewsbury, Widnes and Huddersfield.
There may be four dominant sides at the moment in the Championship but it's unlikely that those four same sides will still be dominating in 10 years' time. Some will be SL sides and others will have been relegated.
Hence Doncaster as a rising power isn't quite a surprise as the rise of Giants and Wire.