An excellent thread and topic, and really interesting reading how they go about proving cause and effect.
I think the way I view it is: If I eventually test XMRV+, then I will have XMRV (or maybe XAND), and the use of the acronym ME will drift away, and disappear in the annals of history, just like GRID (AIDS) did. XMRV won't just be the cause, it will be part and parcel (if obviously proven to be so), and it will have always been there, mistakenly called something else.
I was quite surprised to learn that AIDS was discovered before HIV. So people had AIDS, and no one knew why. But AIDS wasn't it's name then; it was called GRID (Gay Related Immune Disease, as probably most of you know, and even more disparaging then CFS). So when they discovered HIV caused GRID, its name was changed overnight. Like how XMRV wont cause ME, or CFS, but maybe XAND, or some other acronym they will pluck out of the air.
So when people are sick, and they are unaware of the cause, it seems to receive a part time name. The problem with ME is, it has been in recorded history for over 100 years!! And to make matters worse it was renamed CFS, just to confuse everyone.
Proving XMRV causes disease will take time simply watching what it does in experiments. But it is obviously a smoking gun, and called it what you want. Whether it's ME, CFS, XMRV, or XAND, I will still feel lousy tomorrow, and the day after.
But we have to call it something. When people who see me using my cane for the first time, I just say my legs are shot. It's easier, and I don't do small talk these days. But after I'm tested, and the news is what will all expect it to be, well, just try to shut me up then. When I have finished telling people about XMRV, their ears will be ringing!!