While I wouldn't entirely agree with your analysis you have some very good points.Power is shared between Christian fundamentalist Uber British nationalists and neo Marxist Uber Irish nationalists. And its the good people over here that keep on voting them back in.
However I would not describe Sinn Fein as Uber Marxist. They came very close to coming to power in the last election in the South. They are currently morphing into a leftist party.
The DUP is between a rock and a hard place with the Irish protocol and the Brexit.
While the political situation matures there will be still need for power sharing in Northern Ireland. Until sectarian politics is a thing of the past.
While Northern Ireland is still not perfect, it's in a much better situation than 30 years ago.