This whole 'seniority' thing seems to be unduly rigid and 'numerical'. A Squadron may have 'clocked up' many years of unbroken service without having done anything as significant or worthwhile as another with notionally less 'seniority'.
We have already consigned No.19 Squadron (the first Spit squadron, Sailor Malan's mob, arguably the leading Duxford 'Big Wing' unit) to the dustbin, along with No.92 (the most successful RAF fighter Squadron of WW2, if I recall correctly), No.56 (the Firebirds!) and No.74, while No.25 Squadron and No.5 remain in being, despite having had far less distinguished histories.
The idea of assigning Squadron numberplates to what are now flights has a great deal of merit, in my view. Squadrons would be led by Squadron Leaders, for starters, and twice as many number-plates could be kept in being.