Concerning Donegal, Pooka, the presence of Independent Fianna Fail, a local machine dating back to Neil Blaney (one of the Arms Trial Ministers and more republican than the official FF), limits the opportunities for SF there.Regarding the Labour Party, they must be very disappointed that they didn't profit from Fine Gael's losses. Many of the Independents who won seats were running on issues to do with the health service, which ought to be a natural constituency for a Labour party.
It was also noticeable that many Green votes transferred to Labour in places where the Green candidate was eliminated first. Again, this is an area where a worthwhile social democrat party should be picking up votes.
Sinn Fein used to find it very difficult to get votes in the south, even where candidates were working extremely hard. Even now, with the IRA on ceasefire, many potential voters prefer to look elsewhere if a radical left wing alternative exists, such as the Socialist Party or some of the independents.
Not so long ago, the Workers Party/Democratic Left were in a similar position to SF before self-destructing. SF did well in enough in several constituencies to have hopes of further gains next time, but electoral politics is a slow business.
By the way, one point that Unionists will increasingly make is that they have been forced to share power in the north with SF when no party in the south would agree to do so. Even fewer in the south would relish Martin McGuinness as Minister for Education than in the north.
The intervention of SF in southern politics could have some unforeseen effects!