It would help if Noricum wont get romanized, or atleast to a smaller extent, maybe keeping the region bilingual instead of assimilating they natives to the latin language, with latin being speaken and understood by the aristrocracy, but the majority of the people still speaking norish. In this timeline, Noricum might be a part of the Roman empire later, OTL it became part of the Roman empire when claudius became emperor, somehow butterflying him away, and another emperor might not incorporate Noricum that soon. combine that with a earlier collaps of the roman empire and the norican language could survive. Would that be possible ?
But i wonder what influence a earlier collaps could have on christanity. maybwe ther woulc be more different churche sinstead of roman catholic, so there would be a norican church, a french church etc ?