It‘s probably still much less secure than pre-AI FOSS simply because it didn‘t have to deal with that kind of attacks.
The way corporate software will survive is through absurds laws they lobby for and data centers, though. Because if they kept playing by the old rules of consumers owning devices they would lose to FOSS really quickly at this point. With so many vibe coded clones and all. But when the hardware becomes unobtainable for mere citizens most of us will get pushed further and further into the cloud and complete surveillance. I bet that‘s what they‘re betting on.