YOU SAID:

this is bound to be a while

INTO JAPANESE

これはしばらくするに違いない

BACK INTO ENGLISH

This must be a while.

INTO JAPANESE

これはしばらくの間でなければなりません。

BACK INTO ENGLISH

This should be for a while.

INTO JAPANESE

これはしばらくの間であるはずです。

BACK INTO ENGLISH

This should be for a while.