Leaving aside the question of whether or not it would be beneficial, is it likely that resurgent secular nationalism can unify the right and could reverse the cultural suicide of PC?
Because that seems to be an assumption among many of the US based conservative commentators, and an aspiration of rightist commentators from other countries.
But I will argue that a secular nationalism would nowadays have a strongly different character from most secular nationalisms of the past.
A modern nationalism might perhaps save the nation (probably at the cost of fracturing it into smaller nations) - but it would not save the national culture.
When nationalism was an effective political force, it was a movement which was already there, it did not need much encouragement.
In most counties - perhaps all of them - nationalism originated with the ruling elites - often the lower ranks of the elites (i.e. the most numerous ranks): people like school teacher and lower administrators, also journalists and artists.
In other words, past successful nationalisms were led by a high-cultural elite: it was a nationalism of clerks.
In other words, past effective nationalisms originated with exactly those groups which are nowadays the most politically correct, least nationalistic, most in favour of multi-culturalism.
Any modern nationalism would therefore need to be very different from past nationalisms.
The apparent exception of National Socialism is deceptive: German nationalism was a nineteenth century phenomenon, driven by the upper classes. At most the Nazis (who were lower class intellectuals, outside of the normal German elite of aristocrats and Professors) - hijacked this already-existing powerful nationalism: certainly they did not create it. And the Nazis did not so much promote German culture as destroy German High Culture - leaving behind only a much simplified and selective populist folk culture.
Of course new things can happen - and we are, after all, in an unprecedented situation: i.e. the new experience of deliberate, strategic, sustained, cultural and biological suicide by the intellectual elites, taking their nations and cultures with them.
Perhaps such a novel situation will inevitably lead to new and unforseen types of political response? - perhaps including a nationalism which is opposed by the exact groups which (in previous nationalisms) supported it?
In line with this, what does seem to be resurgent in the West (to some extent - maybe limited) is a lower class, populist nationalism.
What we are seeing is a nationalism led by the skilled working class rather than the teachers, lower civil servants and writers - we are seeing a nationalism of tradesman rather than clerks.
(And perhaps tradesman-led nationalism may be much bigger and more powerful than it seems, because it lacks a voice and the hostility of the communications personnel will naturally minimize and misrepresent it. Or maybe it is much smaller than it seems? - because the hatred and fear of the clerks towards the tradesmen leads to the clerks to perceive the threat of new nationalisms as bigger than it really is.)
To be successful, such a nationalism of the tradesmen would, surely, need to be be anti-intellectual and anti-upper class- would seek to replace the effete, irrelevant, decadent clerks with sensible skilled workers?
In such a society, warrior virtues would presumably predominate - courage, strength, loyalty, perhaps common-sense and concrete effectiveness; and there would consequently be few high status, ruling positions for intellectuals, high-artists and abstract thinkers.
In a tradesman-led nationalism, intellectuals would, rather, be allocated subordinate status as servants and functionaries.
(Recall that the bulk of intellectuals - clerks and teachers - in many past civilizations were often slaves, eunuchs and celibates.)
In sum, I do not think it likely that nationalism will again become powerful in modern societies, because the traditionally nationalist clerks are now anti-nationalist; the only possibility is a nationalism of the tradesmen.
But if I am wrong, and nationalism does again become powerful, it would have to be a new kind of nationalism. A new nationalism of the skilled working class: a nationalism of the tradesmen.
And (to mobilize support and maintain cohesion) any effective nationalism of the tradesmen would surely be openly and explicitly anti-intellectual and anti-upper class - which means that it would be 'anti-culture'.
More exactly, under a nationalism of the upper working class/ lower middle class, the complex upper middle class 'high culture' would be radically simplified and selected-from to generate (or regenerate) a popular folk culture which is suitable for the tradesman class - that is, a class who are only secondarily concerned with culture, who do not regard high culture as a primary matter bound up with their personal identity, status and livelihood.
Rather, the lower class leaders are likely to regard high culture with hostility, based on the suspicion (often accurate) that it is a tool for forcing the tradesmen class into subordinate status and for elevating the status of the clerks.
(Note: I have been talking here of secular nationalisms. There are other social possibilities for religious societies that I have not mentioned above.)