The unionists have had their way for over 300 years and change is finally on the way.
But England and Scotland have been separate throughout history for far longer than they have been part of an alliance, so if we're merely taking turns, then we have a very long time left before we're 'even'. You make it sound like 'the unionists' are one specific quantifiable group of people, who conspired and sought to take and keep control. Also, there are plenty of unionists on both sides of the border, as well as plenty of people in E,W&NI (not including me) who are tired of all the complaining and just want Scotland to get on with it and go - it isn't just the nasty English wanting to keep you as perpetual puppets.
You might as well say that the modern British people have had our way for long enough and it's high time for the Vikings/Romans/Picts/Gauls etc to have THEIR lands back.
If the majority of Scots want to leave, as proved by a referendum, then that's what should happen; although, whoever actually calls the referendum to put it to the people will presumably be castigated for doing so as David Cameron was.
However, I really don't understand why the 'official' line (i.e. the one shouting most loudly and overbearingly whilst insulting and branding as bigots anybody who disagrees ) is that maintaining a 40+ year alliance with the EU is the only sensible choice whilst remaining in a 300+ year alliance with England & Wales is clearly madness.