tbh the most frightening development of the populist right will be when they figure out that their Eurosceptic agenda is much less appealing for the general European public (outside of odd Greek bailout style situations) than their anti-immigration schtick. I would not be surprised if the next generation of the populist right synthesizes cuts on migration/repatriation with pro-EU sentiment or even Eurofederalism (i.e. "the forces of Europe and Judeo-Christian values need to come together to fight against the horde etc).
If I remember correctly, Oswald Mosley was quite into something like this in the form of his 'Europe a Nation' policy.
