Maybe Mr Henry Dashwood could not expect the will to be any different than it turned out, but I still understand his disappointment. We are told that "Mr Dashwood had wished for it [Norland] more for the sake of his wife and daughters than for himself or his son". If his uncle had only bequeathed the estate to Henry Dashwood and not to his son and his son's son after him, then Henry Dashwood could have left Norland to his wife, after his own death. Henry Dashwood's main interest is his wife and daughters, and I think he would have liked to leave the estate to them. But that is out of the question now because of Mr Dashwood's will.

But at the same time, you can see why "the old Gentleman" Dashwood would like to make sure that the estate would pass from son to son, so as to keep Norland in the family. If Mrs Dashwood had married again after Mr Henry Dashwood's death, then the estate would become the property of Mr Whoeverheis.