If March hadn't been 5 weeks following launch week it also would have looked worse. It'll be around 80K in April and if that number gets public somehow we'll have one of the busier NPD threads in a long time. I'm thinking weekly in March was 80K, 50K, 35K, 25K, 20K and we'll see 20K a week in April.
That would be my guess as well.
And yes, there will be carnage in the NPD thread.
Eh, I think it'll be at around 100k, just like 3DS in its third month, 80k would be really low, too low.
And, about the 3DS doing poorly, 3DS is doing fine in USA now.
3DS started from a higher water mark, and Vita is already trending below it on a weekly basis. It's going to be low.