Most likely C++ would not happened, while at the same time C and UNIX adoption would never gotten big enough to be relevant outside Bell Labs.

Which then again, isn't that much of a deal, industry would have steered into other programming languages and operating systems.

Overall that would be a much preferable alternative timeline, assuming security would be taken more seriously, as it has taken 45 years since C.A.R Hoare Turing award speech and Morris worm, and only after companies and government started to feel the monetary pain of their decisions.

I think there are very good reasons why C and UNIX were successful and are still around as foundational technologies. Nor do I think C or UNIX legacy are the real problem we have with security. Instead, complexity is the problem.