Volskunie were a mighty party in Flanders that died. The Right of the party re-emerged as the N-VA. The social liberals that dominated it though got vacuumed up in sp.a and Agalev.
Cdh and ecolo in Wallonia (basically could become PS sattelites)
FDF/Défi in Brussels (by virtue of previously being a strong player in Brussels).
The PS(OE) in France and Spain are in far, far more danger than the UK and Dutch Labour party because they have movements that can replace them fairly easily (En Marche and Ciudadanos for the social liberals and democrats, Mélenchon and Podemos for the more left-wing of the party). They are basically being kept alive by traditional voters in certain regions. The UK Labour party will be the only real alternative to the Tories for many, and the Dutch Labour Party still has a high ceiling once D66, GL and 50PLUS will inevitably lose their voters. Only SP is a threat.
I agree for the VolksUnie and the CdH, but why are Défi here? They were never a huge party outside of Brussels and my understanding is they're actually polling pretty well.
Well, they have reinvented and recovered now with ECOLO thanks to the corruption and bad governance of the PS, but let's not forget that FDF were the first party in Brussels a couple of times. Had their split with MR ended badly for them it would have been a surprising disappearance. But yeah, still nowhere near as hegemonic as the PS and cdH(PSC) were once upon a time. Those two are arguably in greater danger.