I know that you all thing that PiS is some kind of ultra-Catholic party and will make second Iran in Poland but as most of the post-Solidarity parties they are mainly focused on power, in case of PiS claiming it after years of political failures and humiliations. As they have no partner for coalition (maybe Kukiz but I doubt if he will be able to get over 5% threshold) they must secure a majority so also they will probably a little bit make get moderate - and as you can see with president-elect Andrzej Duda and female candidate for the PM they are doing it since the beginning of the year.
Right, Kukiz, with his numbers steadily declining, may very well fell below 5% As of other parties, PSL, despite their willingness to enter various coalitions thorough history, seems unlikely junior partner. There's certainly not going to be any POPiS - we're no longer in 2004/2005, when it seemed inevitable for many. SLD would be an odd match, despite Miller's recent signals (The Pimp might be out of any postion after the election anyway and I sincerely hope for SLD to finally drop dead). NowoczesnaPL is another prematurely declining project, just as Korwin, who can't repeat his onetime success in 2014 EP elections.
There's no way PiS can win a majority on its own, just as SLD couldn't in 2001 and PO in 2007. That makes the whole situation extremely interesting. Nothing can be really ruled out.
One thing to remember. PiS didn't suddenly became popular. We're witnessing results of fatigue from PO government which, quite frankly, sucks.