We don't need full organism simulation for this to be useful. We just need tissue and cell level interactions that are accurate to have this be useful in drug search. As we want to look at effects on metabolism etc a coarse grain approach could provide direction.

The computational complexity aspect could be side-stepped if quantum computers were invented before 80 years. One of the few things quantum computers can do exponentially better is simulate quantum mechanics. Biology is chemistry which is "just" a bunch of quantum many body problems. With a QC we can model Protein interactions, RNA, signaling, transport etc much more efficiently than a regular computer.