People - a lot of people - have already died when opposite direction traffic has collided using the same airway. (See the Pprune Home page for details from 1996.) This was one of Pprune's earliest 'crusades', and unfortunately, little or nothing has been achieved since then except a few more line pilots have been made aware of the problem.
Let's be clear about one thing: more people are going to die in midairs unless we as an industry do something about fixing this all too easily fixed problem. It's not good enough for isolated individuals to fly offset. Everyone with the super accurate GPS/INS should do it, and the only way that will ever happen is if the equipment does it automatically.
Every time in the past this has been raised, someone chimes in 'proving' it won't work because of one thing or another. It's all too easy to be dragged off on a tangent with arguments like this. The RVSM camp see their problem, the NATS track people theirs, ATC people see the call for offsetting as an affront or criticism of their professionalism, the mathematicians can 'prove' it makes the risk of collision more likely.
Let's agree that the problem offsetting is attempting to address applies in no way, shape or form with NATS tracks, which have problems unique to the busy (and usually one way at different times of day) traffic patterns North Atlantic. I'm mainly concerned with the non-radar environment outside Western Europe and the US. And I'm not slagging off the controllers in these other parts of the world. It's just that it's a fact of life they are forced to work in a far from ideal environment with sometimes poor or outdated equipment, bad (and sometimes no) comms with neighbouring agencies because of political conflicts. Anyone with any imagination can see the potential for serious traffic conflict in such environments because of the high accuracy of modern navigation systems. The only long term answer is unidirectional airways, but I wouldn't hold my breath waiting for them.
What amazes me is the concerted resistance that people in authority (and therefore not flying the line daily) are maintaining to addressing this navigation accuracy problem. It will probably take at the very least some embarrassing disclosures by some 'muck raking' journalist to shake these agencies into doing something. (Thanks to sites like this, they won't be able to say they or the industry as a whole were unaware the problem existed.) Unfortunately, it's unlikely any such journalist will see any news value in any such story until a lot of people have died in circumstances that cannot be disguised as being attributable to anything but the accuracy of the nav systems. Let's hope that's a long time (if never) coming, but I fear that's a faint hope.