What about Albanian?
Even though, Illyrian has been the first language to be compared to Albanian, Thraco-Dacian is the strongest contestant. A number of linguists have been examining the possibility of Albanian being a descendant of a Dacian relic. The initial Roman conquest of part of Dacia did not put an end to the language, as free Dacian tribes such as the Carpi may have continued to speak Dacian in Moldavia and adjacent regions as late as the 6th or 7th century AD, still capable of leaving some influences in the forming of Slavic languages. According to the hypothesis of Hasdeu (1901), a branch of Dacian continued as the Albanian language. A refined version of that hypothesis considers Albanian to be a Daco-Moesian dialect that split off before 300 BC, and that Dacian became extinct. Strong evidence to this theory is the shared substratum of words in Romanian and Albanian.".
This assertion rests on the very disputable, if not already obsolete, assumption that Romanian stems from Dacian. While some Romanians might have partial Dacian ancestry, the Romanian language probably moved there from South of the Danube in the Middle Ages.
And in addition to linguistics, note that Albanian and Moldovan Y-DNA lines have almost nothing in common, while there is very little in common between Albanians and Romanians. And among the few paleo-Balkan lines they do share, the ones that have been researched best were clearly in the Western Balkans Classical or Late Antiquity.