I think there will always be vendor lock in. The same way there have been architectural differences between Intel and AMD's x86, or even stuff like one specific chip/family tanking performance because one instruction was implemented differently, you won't be able to guarantee efficient utilization of different vendor/families.

For example, I've taken code optimized for Xilinx, ran it for another vendor, and resource count ballooned because stuff that was built-in/free on one wasn't on the other. It's a lot of work to truly make generic code and usually just means switching out modules per vendor.