My question now is, do you believe The Lancet will now publish an article on or print a retraction of the PACE study? Has The Lancet ever been in such a situation before?
Yes. They retracted the Wakefield study on Autism which was high profile and a long drawn out ordeal. I am sure they have retracted others. Retractions aren't all that common in scientific publication, but not unheard of. It does highlight the problems with peer review in it's current form – especially at the Lancet. I'm sure the editors are concerned about their image if they had another high profile study fail after it was published.
From a big picture perspective, I am somewhat ambivilent about retractions. In the case of clearly falsified or manipulated data/conclusions or conflicts of interests it is warranted. But in the case of scientists making honest mistakes it probably isn't. It essentially erases potentially useful data from the scientific record and forever tars those associated with the paper. What probably should happen is a follow up written explaining why the original conclusions were wrong, and then others can comment on it so the record stands corrected. That way, someone else can learn from the mistakes and take any valuable data and plan future studies on the same topic, but not make those same errors.
To be clear, I feel PACE is clearly in the former category, XMRV was probably the latter.