[saltcured]

You're saying that as if survival doesn't remain an evolutionary pressure. Life is inherently demanding, and many mutations are lethal.

So, at best, the argument seems to be that the surviving gene pool may get more complex with lots of optional mutations which all coexist? Could we end up like some plant species full of cultivars where larger swathes of genes are expressing differently out of a very convoluted library?

If you're envisioning medical science to allow people to survive with otherwise lethal mutations, I would say that is not an escape from evolution. Instead, you've revised the reproductive cycle to include more epigenetic components. The species is still the survivable set of genes and cultural practices which are evolving together, and which terminate when they no longer function as a system.