I think at a first week between 50k and 100k. However,I think it could do more than 50k,because the preorder will increase in the remaining days,on Amazon it is 18th with the normal version,29th with the version including OST,so it has a double presence XD
Remember,it is even third in the chart of most awaited games from Famitsu's readers,behind DQX and MH3rd,not THE factor about its possible sales,but always something.
Zangeki made 22k staying at 25th place on Amazon for an half of a month,but without any presence in top20 on COMG(and the 20th position was at 20pts,so it was VERY low).
We should see what happens in other retailers,however.
I'm praying for 75k,at least,first week and even 200k of LTD XD