I won't say that this has no chance of succeeding, even though that is the most likely outcome. But it is these kinds of blind and reckless experiments that will bring new understandings that can potentially add more knowledge that will make a success later on. Yes, that sentence was that long because that is how much importance this experiment will hold in the end.

They tested the genes on single cells or at best a couple of them together. I guarantee you that these cells won't even make it past the embryonic stage unless dramatic changes are introduced to the procedure. Gene expression is easy. The hard part is how to seamlessly integrate that extra gene into a network of densely expressed native genes, all of which interact and regulate with each other, and not disrupt any of them. Because if even just one in a few thousands get affected, like say instead of making 100 copies, it makes 90, then that fetus will likely become nonviable.

So we aren't going to make Space Marines anytime soon. Unless they manage to change all somatic cells in a human body at the same time, at which point it probably more likely the AGIs are in charge already.