Just to clarify for people, the Wii's highest week so far (in 2009, in the UK) is 48K. It did 35K last week, so we're looking at an increase of ~ 50%.
The chances of Ps3 or X360 beating that are rather slim, seeing at the Ps3 was at 24K last week, and the X360 was at 18K. This would thus require a doubling and tripling in sales, which is incredibly unlikely.
Even with an overall (Europe/Worldwide) Wii increase of 30-50%, I don't see any meltdowns coming. This would mean we're looking at ~ 500K of Wii sales, and 400K + for Ps360.
If there are to be any meltdowns, they would have to be software wise, I'd say. Although I don't really see what they would be.
Unless, of course, VGChartz numbers differ a lot, and that is what the meltdown will be about. However, I cannot see why ioi would be happy about that.
All in all, I cannot see any specific reason for a meltdown. Oyvovy predicts: no meltdowns (as in, nothing more than the usual)