Considering that the bulk of illyrian tribes sat in Bosnia, slovenia and croatia and that Vudedol culture was proto-Illyrian, the only logical scenario is this
Bosnia ......were many Illyrians who gained some slavs after 600CE became slavic later
Croatia .....were illyrians who became slavic due to the settlement of many slavs
Dalmatia............were illyrian as much as Bosnians who became slavs very late in time.
slovenian and eastern Austrians ( noricum area )..........were illyrians who became firstly bavarians then slavs , then east austria became bavarian again.
The percentage of illyrians who became albanians is very very small, we see this in the DNA
from top to bottom, ......which ancient ethnicity make up the albanians
Dardanians
Epirotes
Macedonians
Illyrians
Corinthinan Greeks
Dorians
Clearly you must realise that the Ghegs are "proper Albanians" and the Tosks are less so
But since Brittania states that Albanoi first appeared in 200CE ( common era (after christ )), it would be logical to say from this date, there was no longer any Dardanians, Illyrians and Dorians..so claiming any of these ethnicities is a fabrication