There is no indication of a sea change in nationalist areas yet, but:

Given the dramatis personae, it will not take Sherlock Holmes to persuade the Taoiseach and most others except Sinn Fein, that they were right all along to blame the Provos. However it was the events in the Markets area of Belfast as they unfolded which first showed that Sinn Fein was not completely invulnerable to public opinion in their strongest areas, and that that opinion was outraged by what was going on.

It's as if Sinn Fein was unconscious of the message the killing sent to its own constituents:

The killing had no political purpose (as if that would justify it), it served the ends of no organisation, unless that were to instil terror. It was the result of a vulgar brawl, an act of personal revenge and great brutality. And yet, the first instinct of IRA and Sinn Fein was to close ranks, to cover up, to defend the indefensible because those concerned were prominent enough in the movement that they could neither be disowned or discovered. This was to disregard moral values, the suffering of the family in their quest for justice, and the feelings of the community.

One of the most damaging things (although it may not be the most damaging) is the sense that the party is moving backwards at a pace clearly not of their own choosing:

The first reaction was to applaud the rioting children and to complain of police heavy-handedness. Then it was tell somebody, tell anybody, but not the police. Finally it was tell the police if you must, or someone in authority. Intimidation too was disowned as the days passed, finally even by the IRA. And eventually too, a definition of justice as arrest, trial in the courts, conviction and imprisonment was dragged from a spokesman as Sinn Fein began to come into the real world.