I'm genuinely curious if this has been "decided" anywhere by credible researchers.

South Slavs have a different stock of haplogroups than Northern Slavs, and cluster together rather than with other European groups. Clearly we're our own family-branch.

Coincidentally the people with the highest portion of M423 also dwell in what the Romans and Greeks labelled Illyria. Although most people think the Illyrians simply vanished after their Latinization, some kept their ethnic identity for a long time (such as the Barracks Emperors, Belisarius, etc.). I know the Balkans were generally a war-zone for the late Roman Empire and barbarian tribes, but did the Illyrians really just vanish (again)? I mean, Albanians claim to be of that stock but have more in common with Greeks genetically than South Slavs, and Albania was generally a kind of borderline between Illyria proper and Greece (Epirus).

Historically it was said that many Roman cities on the Croatian coast remained free and independent of the "migrant Slavs" and Latin Dalmatian was spoken well into the 1800's (from what I recall). Haplogroup I2 spikes in Dalmatia and Bosnia, one packed with seemingly peaceful Illyrian towns, the other a mountainous escape for natives from invading foreigners.

I mean, from the mosaics of Roman-Illyrian Emperors and Generals in Byzantium, I can definitely see more of a resemblance to many Southern Slavs than I can when comparing typical Bosnians to typical Russians. At the same time there is definitely a Slavic (or whatever northern European tribe) mix in Balkanians for sure, but mainly were we simply Slavicized after the collapse of the Western and Eastern Roman Empires?

Croatians were historically referred to as Illyrians, Serbs were synonymous with Tribalians (Thracian tribe), and Bosnia is named after the Bosona river (an Illyrian word if I recall correctly). I mean people of haplogroup I are noted for being particularly tall, the Greeks and Romans both described Illyrians as particularly tall people.

Can they ever dig up Illyrian bones and sequence their haplogroups?