One of my major concerns with this Cabinet shuffle is that the prime minister has no plans to replace Senator the Honourable Marjory LeBreton P.C. (Ontario), the Leader of Her Majesty's Government in the Senate, at the Cabinet table. While he has indicated an intention to consult with the Conservative caucus in the Senate before the appointment of a "leader," speculation is that this person is not going to be a minister with the Government.
Cutting the link between the Government caucus in the Senate, and the Cabinet, is a dangerous game that the prime minister is about to embark on. Without that direct channel of communication between the Government and its Conservative caucus in the Senate, the Government is at even more risk than it is now of Conservative senators voting down Government-backed bills. (Which is fantastic, in my opinion -- just an absolutely bizarre tactical choice for a prime minister who has loved control.)
This also presents extreme procedural problems for the Senate. Currently, only ministers can rise to respond to oral questions in the Senate on matters of Government policy. The effect of a failure to appoint a minister out of the Upper House will mean that the Government will not have an official voice in the Senate (and that the Senate may be unable to discharge its constitutional authority to hold the Government accountable for its performance and conduct).
I hope that the Senate recognises this decision of the prime minister as the parliamentary contempt that it is, and that senators on both sides of the House come together to frustrate the prime minister's agenda until he agrees to deal and correspond with the Senate in a professional and mature manner.
The prime minister needs to recognise that he cannot simply get rid of the Senate by refusing to appoint senators (as he attempted for several months near the start of his Government), or by refusing to have a properly-constituted Government caucus. The Senate has constitutional functions that must be discharged under the Constitution Act, 1867, and it will continue to perform those functions with or without the prime minister. It's in his own interest to play by the rules.