Yes and no, the fact you have a concept of culture doesn't mean nationalism will arise inevitably, concepts of culture are something literally from the get-go of human society and took until the 1790s-1800s to develop nationalism (and even then the spread of nationalism wasn't as quick as many people think, a lot of early 19th century stuff is explained as "but the inevitable force of nationalism!!!!!" when it actually has much more to it and sometimes literally has nothing related to nationalism), for much time the concept of culture wasn't very related to statehood, even pan-[insert culture here] was rare to be seen. Nationalism arose because France needed something to put its people together and after the french took over Europe this feeling ended spreading. I mean, it is possible that nationalism may arise, but chance is to it remain a localized thing (due to the nation in which it rose ending up not being the hegemon of an entire continent), and even then it isn't inevitable that nationalism rises, equally as it isn't inevitable that nationalism never rises.The concept of culture existed before 1800 and so the concept of nation of the people( france, England, Spain are an example).
in OTL the events of the XIV century showed how powerful can be the people of same culture if they stood united.